Five terms, one line each
SEO (search engine optimization): be found and ranked in search engines. AEO (answer engine optimization): be the answer a search or voice feature gives. GEO (generative engine optimization): be named in answers written by AI. AI SEO: the broad name for search work aimed at AI engines. LLM SEO: the same, named after the large language models behind them.
Where the work is the same
All of it needs pages that engines can fetch and read, a company that machines can identify, content that answers real questions, and other sites that vouch for you. Google’s own guidance on its AI features says the usual SEO best practices apply. If your SEO is weak, GEO will not save you.
Three things that really differ
The goal. SEO counts positions; GEO counts mentions. In a list of ten links, position seven is still seen. In an answer that names three businesses, a fourth place does not exist.
The measurement. Rankings are fairly stable and tools track them. AI answers vary between runs and per engine, so you need fixed questions, several runs and the raw answers kept.
The weight of other sources. AI engines lean heavily on what others write about you: lists, comparisons, reviews, trade press. In GEO, earning those mentions is a main task, not a side task.
Which one do you need?
You do not need three agencies or three budgets. You need the shared base done well, and someone who measures what the AI engines say about you and works on the sources they cite. Whatever the label, ask to see the raw answers.
Start with the free check for the base, or read what GEO is and what AEO is in more depth.