The real difference is not price. It is who does the work and how many layers sit between your business and the person clicking the buttons.
Cost, honestly
Agencies typically charge $1,500–$8,000 a month or 10–20% of spend. Freelancers typically charge $500–$2,500. The gap is overhead: account management, sales, offices and junior staff time.
That overhead is not automatically waste. It buys capacity and continuity. It is waste when it buys layers you do not need.
Seniority in the account
At most agencies the senior strategist wins the account and a junior runs it. With a freelancer, the person you assessed is the person working. If your account needs judgement rather than volume of hands, that difference dominates everything else.
Capacity and risk
Agencies cover illness, holidays and sudden scale-ups. A freelancer does not. If your business would be materially damaged by two weeks without account changes, price that risk in — or agree a documented handover and access policy up front.
Breadth of services
If you need PPC plus creative production, SEO, CRO and development coordinated, an agency is genuinely simpler. If you need paid media and measurement done well and you have the rest covered, that breadth is something you are paying for and not using.
How to decide
Under $10,000 a month in ad spend, a specialist freelancer is usually better value. Between $10,000 and $50,000 it depends on how many disciplines you need. Above that, most businesses want either an agency or an in-house team with a specialist consultant alongside.
Whichever you choose, insist on owning your accounts, seeing cost per lead rather than clicks, and understanding how conversions are measured. If you want an independent read on your current setup first, take a paid media audit.