What is the difference between AEO and SEO?

What transfers from SEO

A lot. Crawlable pages, clean site structure, structured data, consistent business records across the web, content that actually answers questions: all of it matters to both. A site that is invisible to Google's crawler is invisible to answer engines too. If you have done serious SEO work, none of it is wasted.

What changes

The measurement changes first. Rankings are stable enough to check weekly with standard tools; generated answers vary by engine, by day, and by run, so AEO measurement means asking the real questions repeatedly and reporting how often you were named, engine by engine. A single check proves nothing in either direction.

The fix list changes second. SEO work tunes pages toward ranking signals. AEO work tunes facts toward quotability: a rate that exists only inside an image or a rate widget cannot be quoted by a model, and a fee schedule written as marketing prose loses to a competitor's one-sentence plain statement of the same fee.

The competition changes third. On a results page you compete for position against everyone. Inside a generated answer, the engine has already decided the category; the contest is whether the two or three names it picks include yours. Being the fourth-best answer earns nothing at all.

Do you need both?

Yes, and they are usually different efforts. Most institutions keep their SEO agency for the link-list work and treat AEO as its own measured program, because the leaderboards genuinely differ: who ranks on Google and who gets named by the engines answering the same question are often different lists. Measuring both is the only way to know how different they are for your metro.