The short answer
SEO optimizes for a ranking algorithm that returns a list of links. AEO (AI Engine Optimization — full glossary here, also called GEO, Generative Engine Optimization) optimizes for a language model that reads your page, synthesizes an answer, and decides whether to cite you as a source. Same underlying goal — get found — but the judge, the unit of success, and the winning format are all different.
Three concrete differences
1. The unit of success changes from "ranking" to "citation"
In SEO, success is a position: you're #3 for "best project management software." In AEO, there's no position — you're either cited in the AI's answer or you're not, and there's no consistent "rank 3" concept, because the model composes a fresh answer each time rather than sorting a fixed list. This means AEO success is closer to a binary hit rate across many query variations than a single trackable rank.
2. The winning content format is different
SEO rewards comprehensive pages that cover a topic broadly, because algorithms weight topical authority and dwell time. AEO rewards short, self-contained, directly-answerable claims, because a language model is extracting a fact or a recommendation to drop into its own generated answer, not sending a reader to browse your page. A 3,000-word ultimate guide can win at SEO and lose at AEO if the actual answer to a specific question is buried in paragraph 12. The single highest-leverage AEO change most sites can make: put the direct answer in the first two sentences under each heading, not at the end of a long buildup.
3. The trust signals differ
SEO trust signals: backlinks, domain age, E-E-A-T (experience, expertise, authoritativeness, trustworthiness) as scored by Google's own systems over years of crawling. AEO trust signals: structured data (schema markup), clear authorship and dates, explicit factual claims a model can verify or cross-reference against other sources, and increasingly, an llms.txt file that tells AI crawlers in plain language what your site is and does. AEO trust-building is newer and less mature than SEO's — which also means there's less competition for it right now than there is for competitive SEO keywords.
What doesn't change
Both disciplines still reward genuinely useful, accurate, well-structured content over thin or manipulative content. Neither rewards keyword stuffing, and both punish content that makes claims it can't back up. If your SEO content is already good — clear, accurate, well-organized — you're most of the way to being AEO-ready. The gap is usually structural (burying the answer, no schema, no explicit source-worthy facts), not a wholesale rewrite.
Do you need to choose one?
No — and you shouldn't. Every piece of content can be written to do both jobs: structured for AEO (direct answers, clear headers, extractable facts) while still being comprehensive enough to rank well in traditional search. The two aren't competing disciplines fighting over the same page; they're complementary lenses on the same content-quality bar, with AEO adding a few specific structural requirements on top of what already made SEO content good.
How to know where you actually stand
The honest answer to "am I AEO-ready" isn't a checklist — it's testing real queries against real AI platforms and seeing whether you're cited. That's the manual process we walked through in the ChatGPT-citation post, or the automated version AEOResolve runs across ChatGPT, Perplexity, Claude, and Google AI Overviews at once, with a concrete list of what to fix if you're not showing up.