People often use "job description" and "job advert" to mean the same thing. They are not the same. A job description is the internal HR document that defines a role in full. A job advert is the external, candidate-facing version you write from that description to attract people to one opening.
The simplest way to picture it: the description is the spec, the advert is the pitch. The description comes first and stays on file. The advert is a shorter, persuasive subset of it that comes down once the role is filled. This post covers those differences and how to turn one into the other.
Key takeaways
- The job description is internal and authoritative. The job advert is external and persuasive, and it is derived from the description.
- The description is fact-driven and at least a page long. The advert should be shorter and treated as a marketing tool.
- On LinkedIn, short posts of roughly 1 to 300 words get about 8.4% more applications per view than average, and candidates spend roughly 14 seconds deciding whether to apply.
- Under the ADA, a written job description prepared before advertising or interviewing counts as evidence (not conclusive) of a role's essential functions.
- Many US states now require a pay range in job postings, so the advert often must show a salary range aligned to the internal pay band.
- Write the description first, then derive the advert from it so both documents stay consistent.
Why it matters
Getting the two mixed up costs you in both directions. If you post your full internal description as an advert, it is too long and too dry to attract people. On LinkedIn, short posts of roughly 1 to 300 words get about 8.4% more applications per view than average, while long posts of 601 words or more get only about 1% more. Candidates spend roughly 14 seconds deciding whether to apply, so length matters.
Get it wrong the other way and you lose your internal record. The description is what you use for pay grades, performance reviews and accommodation requests. Under the ADA, a written job description prepared before advertising or interviewing is treated by the EEOC as evidence (though not conclusive) of the role's essential functions. A description written after a dispute does not carry that weight. So you need both documents, each doing its own job.
The key differences
Purpose
The description defines what the job is in detail. It is a reference for the manager and employee and a basis for pay, reviews and compliance. The advert's purpose is narrower: attract good candidates to one opening.
Audience
The description's audience is internal: the employee, the supervisor, management and other staff. The advert is an external marketing tool aimed at potential candidates outside the company.
Tone
The description is fact-driven and analytical, meant to be used mechanically for internal purposes. The advert is persuasive and scannable, written to get outsiders to apply. It leads with why the role matters.
Length
The description is thorough and typically at least a page long. The advert should be shorter and treated as a marketing tool. LinkedIn data shows short posts attract more applications per view, and Appcast benchmark research points to roughly 201 to 400 words as a strong range for apply rates (exact figures vary by report year).
Contents
The description carries the full duties, essential functions, reporting line, required and preferred qualifications, and physical and mental demands. The advert keeps only the essential functions and core qualifications, then adds employer brand, benefits, salary range and a clear call to action.
Lifecycle
The description is created and maintained first, often before the role is even approved, and it persists after the hire for onboarding, performance and pay. The advert is derived for a specific opening and is taken down once the vacancy is filled.
Legal angle
A written description prepared before advertising or interviewing is treated by the EEOC as evidence, though not conclusive and weighed alongside other evidence, of essential functions under the ADA. Adverts carry their own duty: many US states now require a good-faith pay range, and sometimes a benefits description, in job postings.
Job description vs job advert, side by side
| Dimension | Job description | Job advert |
|---|---|---|
| Purpose | Define the role in full for internal use | Sell the role and attract candidates |
| Audience | Internal: employee, supervisor, management | External: potential candidates |
| Tone | Fact-driven and analytical | Persuasive and scannable |
| Length | Thorough, at least a page | Shorter; ~201 to 400 words performs well (Appcast) |
| Key contents | Full duties, essential functions, qualifications, working conditions | Essential functions, core qualifications, brand, benefits, CTA |
| Lifecycle / when used | Created first; persists after hire for pay, performance, onboarding | Derived for one opening; removed once filled |
| Salary | Internal pay band for equity and budgeting | Public salary range, often legally required |
How to turn a job description into an advert
Step 1: Start from the description
Indeed advises beginning with the job description, then using that information to write the posting. Have the finished description, and in UK and CIPD practice the person specification, in front of you. Together they are the basis for the advert.
Step 2: Lead with the why
Open with why the role matters, not a list of duties. The advert is persuasive, so the first lines should give a candidate a reason to keep reading in the roughly 14 seconds they spend deciding to apply.
Step 3: Keep only the essential functions and core qualifications
Pull the key selling points from the description. Keep the essential functions and the core required qualifications, and cut the marginal duties and internal detail that belong in the description but not the advert.
Step 4: Add brand, benefits, salary and a call to action
Add employer brand, benefits and a clear call to action. Include a salary range: in LinkedIn survey data, 91% of US respondents said a salary range would affect their decision to apply, and many states now require a range in the posting. Align it to your internal pay band.
Step 5: Tighten the length for scanning
Cut the advert down so it scans fast. LinkedIn data favours shorter posts, and Appcast benchmark research points to roughly 201 to 400 words for strong apply rates. Keep the title tight too: Appcast finds 4 to 6 word titles deliver the strongest apply rates.
Step 6: Check for inclusive, bias-free language
Remove biased or masculine-coded wording. LinkedIn notes that words like "aggressive", "dominant" or "rock star" can discourage women from applying, and that on average men apply about 13% more often than women after viewing a role. Inclusive language widens your pool.
Do this
- Write the job description first, then derive the advert from it so both stay consistent.
- Lead the advert with why the role matters, not with a list of duties.
- Keep the advert short and scannable; aim for a tight word count and a 4 to 6 word title.
- Include a salary range in the advert, aligned to your internal pay band and any state requirements.
- Document essential functions in the description before you advertise or interview.
- Use inclusive, bias-free language and remove masculine-coded words.
- Review and update the description regularly to reflect changes in the job.
Common mistakes to avoid
Posting the full description as the advert
The description is fact-driven and at least a page long. Used as an advert, it is too long and too dry. LinkedIn data shows long posts of 601+ words get only about 1% more applications per view than average, versus about 8.4% more for short posts.
Treating the advert as your official record
The advert comes down when the role is filled. If you rely on it instead of a maintained description, you lose the internal record used for pay, reviews and ADA evidence of essential functions.
Leaving out the salary range
In LinkedIn survey data, 91% of US respondents said a salary range would affect their decision to apply. Many states also now require a good-faith range in the posting, so omitting it can break the rules and cut your apply rate.
Writing essential functions after the fact
Under the ADA, a description prepared before advertising or interviewing is treated by the EEOC as evidence of essential functions. One written after an alleged discriminatory action does not carry that weight.
Using biased or vague language
Masculine-coded words can discourage women from applying. Vague titles hurt too: Appcast finds apply rates drop once titles exceed about 10 words. Be specific and inclusive.
Letting the two documents drift apart
If the advert is not derived from the current description, the role you advertise stops matching the role you defined. Derive the advert from the description to keep them consistent.
Frequently asked questions
Is a job advert the same as a job posting or job ad?
Yes. A job advert, a job posting and a job ad all refer to the same external, candidate-facing document. "Job advert" is the more common UK term, while "job posting" or "job ad" is more common in the US.
Which comes first, the description or the advert?
The job description comes first. It is created and maintained first, often before the role is even approved. The advert is derived from it for a specific opening and is taken down once the role is filled.
Do I legally need a job description?
The ADA does not require one, but a written description prepared before advertising or interviewing is treated by the EEOC as evidence (not conclusive) of a role's essential functions. A description written after a dispute does not carry that weight, so preparing one in advance helps.
Do I have to show salary in the advert?
Often, yes. Many US states now require a good-faith pay range, and sometimes a benefits description, in job postings. Beyond the rules, in LinkedIn survey data 91% of US respondents said a salary range would affect their decision to apply.
How long should a job advert be?
A job advert should be shorter than the description. LinkedIn data shows short posts of roughly 1 to 300 words attract about 8.4% more applications per view than average, and Appcast benchmark research points to about 201 to 400 words as a strong range for apply rates.
What is a person specification?
A person specification is a companion internal document, common in UK and CIPD practice. It lists the essential and desirable skills, experience and attributes a candidate needs. Together with the job description, it forms the basis for writing the advert.
The bottom line
Think of the two documents as one source and one pitch. The job description is the internal spec: thorough, fact-driven, and kept on file for pay, performance and compliance. The job advert is the short, persuasive version you derive from it to fill one role, then remove once it is filled. You need both, and the advert should always come from a current description so the two stay consistent.
Write the description well and the advert gets much easier to write. Lead with the why, keep the essential functions, add brand, benefits, salary and a call to action, then tighten it for scanning.
From advert to client-ready CV
A good advert brings the right people in. RefineCV then formats their CVs into clean, branded documents for your client in one step. Try it free with 10 CVs, no credit card.
Related reading: how to write an effective job description and candidate experience and why it matters.
Sources
- LinkedIn Talent Solutions, Stats That Will Change the Way You Write Job Posts (Accessed 2026): Short LinkedIn job posts (roughly 1 to 300 words) get about 8.4% more applications per view than average; long posts (601+ words) get only about 1% more; candidates spend roughly 14 seconds deciding whether to apply. Masculine-coded words such as "aggressive", "dominant" or "rock star" can discourage women from applying, and on average men apply about 13% more often than women after viewing a role.
- LinkedIn Talent Solutions, Should You Include Salary Ranges on Job Postings? (Accessed 2026): In LinkedIn survey data, 91% of US-based respondents said including a salary range in a job post would affect their decision to apply.
- U.S. EEOC, The ADA: Questions and Answers (Accessed 2026): Under the ADA, a written job description prepared in advance of advertising or interviewing is considered evidence (though not necessarily conclusive) of a job's essential functions; a description prepared after an alleged discriminatory action is not given that weight.
- U.S. EEOC, The ADA: Your Responsibilities as an Employer (Accessed 2026): The EEOC treats the employer's judgment and a pre-prepared written job description as important evidence of essential functions, but not the only or prevailing evidence; it is weighed alongside other relevant evidence.
- Workology, The Difference Between a Job Description and a Job Post (Accessed 2026): A job description is internal (audience: employee, supervisor, management) and used for pay grades and performance reviews; a job posting is an external marketing tool to attract outside talent. Job descriptions are fact-driven and analytical and typically at least a page long; job postings should be shorter and treated as a marketing tool.
- SHRM, How to Develop a Job Description (Updated 2024-11-20): Job descriptions should define essential duties, specify required knowledge, skills and abilities and physical or mental demands, remain free from biased language, and be reviewed and updated regularly. The same description is used for postings, interviews, accommodation requests, compensation reviews and performance appraisals.
- Indeed for Employers, How to Write a Job Description (Accessed 2026): Indeed advises beginning with the job description, then using that information to write a strong job posting; the posting is intended to sell the position with an engaging hook.
- Appcast, Recruitment Marketing Benchmark Report (2025 report (2024 data)): Appcast benchmark research indicates job postings of roughly 201 to 400 words tend to achieve the highest apply rates, with rates falling for shorter and much longer postings; exact figures vary by report year.
- Appcast, Job Ad Content Best Practices (Accessed 2026): Appcast reports job titles in the 4 to 6 word range deliver the strongest apply rates, and apply rates drop when titles exceed about 10 words.
- Paycor, Pay Transparency Laws by State (2026): Multiple US states now require employers to include a pay range (and often a benefits description) in job postings, with several new laws taking effect in 2025.
- Tiger Recruitment, Five key differences between a job ad and a job description (Accessed 2026): Recruitment guidance frames the job description as describing in detail what a job consists of (a reference for manager and employee), while the job advert sells the job with short, exciting language; the description and person specification provide the basis for the advert.
- Fraser Dove International, The Difference Between Job Descriptions and Job Adverts (Accessed 2026): The job description is written first and informs recruitment; recruiters derive the advert from it by extracting key selling points, maintaining consistency across both documents.