The two terms started out measuring different things
GEO, generative engine optimization, comes from a research paper by Aggarwal and colleagues at Princeton and IIT Delhi, first posted in November 2023 and published at KDD 2024. Its visibility metrics score a source: how many words of the generated answer cite your page, weighted by how early they appear, plus a language model's rating of how much that citation would draw a reader's attention. In that founding sense, GEO is about your content being used.
AEO, answer engine optimization, has no single origin we could pin down, so we'll take the definition from HubSpot, which named a product after it. It launched HubSpot AEO in April 2026 and defines AEO as improving how often your business appears in AI-generated answers. That is about your brand being named.
Those are genuinely different numbers. An answer can name you without citing your site, and cite your site without naming you. If the market had kept that split, the question in the title would have a clean answer. It didn't.
In 180 answers, the engines used GEO 64 times and AEO 31, for the same vendors
From October 4 to 8, 2026, we put 25 buyer questions about AI visibility tools to ChatGPT, Perplexity, Claude and Google AI Overviews, 180 answers in all. None of the questions used either acronym. GEO or its full name appeared in 64 answers (36%, 95% interval 29% to 43%). AEO appeared in 31 (17%, 12% to 23%). Fourteen used both, often as a single phrase like "AEO/GEO".
The labels didn't sort vendors into two camps. The vendor named most often in our sample appeared in 104 answers: 37 called the category GEO, 11 called it AEO, 11 used both. On October 8, ChatGPT described that same vendor as for "sophisticated GEO teams" in one answer and "serious AEO" in another. Of the five vendors named most often in GEO-only answers, four were also in the top five of the AEO-only answers.
The one name that leaned hard to one side was HubSpot: 6 of the 7 answers that named it said AEO. That's because AEO is in its product's name. The label follows the vendor's branding, not a difference in what the tools measure.
Each engine has its own habit, and search volume is close to even
Google AI Overviews said GEO in 28 of its 45 answers and AEO in 10. ChatGPT said GEO in 23 and AEO in 14. Claude said them in 10 and 6. Perplexity barely used either: 3 and 1. The phrase AI visibility appeared in 125 answers, more than either acronym, though 7 of our 25 questions used it themselves, so some of that is echo.
Buyers are split too. US monthly Google searches, from Google Ads data via DataForSEO on October 8, were 880 for "aeo tools", 720 for "geo tools" and 720 for "generative engine optimization tools". Some of the "geo tools" searches will be people looking for mapping software.
Which one you need comes down to two numbers, under any name
Skip the acronym and ask any tool, AEO or GEO, to show you one buyer question from your category with two results side by side, per engine:
- Was your brand named in the answer? This is the AEO sense, and the number most dashboards lead with.
- Was your site one of the sources the engine cited? This is the GEO paper's sense, and it tells you whether your pages are feeding the answer or someone else's are.
One tool with both numbers beats two tools with one each
The two numbers move separately and point to different work. Named but not cited means engines are learning about you from other people's pages, so your own pages are the gap. Cited but not named means your page is being used to recommend someone else. A tool that reports only one of them will hide the other problem, whatever it calls itself.
Proofsource reports both for every tracked question and engine: mention rate with a Wilson interval, and the sources each answer cited, with the answer text one click away. We have a page called AEO tool and a page called GEO tool, and they describe the same product, because buyers search both words.
Where this could be wrong
The sample is one category, AI visibility tools, over five days and four engines. It is also the category whose vendors write most of the pages that use these terms, so engines may simply be repeating them. Other categories may use the labels differently.
Some of our questions named vendors, as head-to-head comparisons or requests for alternatives, which raises those vendors' counts. We counted a term if it appeared anywhere in an answer, which can't tell a label applied to a tool from a passing mention.
The definitions here are one academic paper's and one vendor's. Some vendors expand AEO as AI engine optimization, and others draw the line between the two terms somewhere else.
