The acronyms multiplied faster than the discipline matured, so here is the cleanest separation we can defend. Reasonable people draw the lines slightly differently - the labels matter less than knowing which job you're doing on a given day.
SEO: earn retrieval
Search engine optimization remains the foundation, and not just for Google traffic. Answer engines that browse lean heavily on conventional search results to decide what to read. The Ahrefs study of 1.4 million prompts found search-sourced content cited 88.5% of the time in ChatGPT answers, against 1.9% for Reddit. If your page doesn't rank, most retrieval systems never fetch it, and everything downstream is moot. SEO's success metric is unchanged: rankings and organic traffic.
GEO: earn the citation
GEO as a named discipline comes from the 2023 paper by researchers at Princeton, Georgia Tech, IIT Delhi, and AI2 (arXiv:2311.09735, later published at KDD 2024), which showed that content-side changes - adding citations, quotations, and statistics to pages - lifted visibility in generative engine answers by up to 40% in their benchmark. The unit of success is the citation: your page named as a source inside a generated answer. GEO work is mostly on-page: extractable claims, specific evidence, clear structure.
AEO: manage the answer itself
Answer engine optimization is the widest lens, and the one we build for. An AI answer can mention your brand, rank you against competitors, describe you accurately or wrongly, and recommend you or hedge - all without citing any page you control. Models also answer from training data with no retrieval at all, and no citation strategy touches those answers. AEO asks: across the prompts that matter to your business, how do answer engines actually talk about you, and is that changing? Its success metrics are presence, position, sentiment, and framing - measured over time, across engines.
Where they overlap
- A page that ranks (SEO) is far more likely to be retrieved, which is the precondition for citation (GEO).
- A cited page (GEO) influences how the answer frames your brand (AEO).
- Entity consistency helps all three: search engines, retrieval layers, and models all reward an unambiguous brand.
- Almost none of the execution work is triplicated - one well-built page serves all three jobs.
Where they diverge
Measurement. An SEO dashboard cannot tell you that ChatGPT describes your product as legacy software, and a citation tracker cannot tell you that Claude recommends your competitor first in nine answers out of ten. Those are AEO facts, and they require asking the engines directly, repeatedly, and reading what comes back. That's the layer we work at: ClerAEO tracks ChatGPT and Claude today, with Perplexity, Gemini, and Copilot rolling out.
If you're allocating effort: keep doing SEO, apply GEO findings to the pages behind your money prompts, and measure at the AEO layer - because the answer, not the ranking, is what your buyer now reads.