Every platform shift mints new acronyms, and the agent era has minted a pile. Most reduce to three genuinely distinct disciplines. It's worth being precise, because they optimize different steps of the same funnel — and stopping one step early is where the money leaks.
SEO: can you be found?
Search engine optimization is the mature discipline: ranking in the index a human (or an agent) queries. It remains foundational — agents route through search constantly — but its unit of success is a visit. It has nothing to say about what happens after arrival.
AEO: are you the answer?
Answer-engine optimization targets the synthesized response — being the product an assistant names, the source it cites. The unit of success is a mention. Valuable, growing, and still fundamentally about visibility: you can be the answer and remain impossible to transact with.
AXO: can the agent complete the task?
Agent experience optimization starts where the other two stop — after the click, when a machine attempts the job it was sent to do: sign up, add to cart, check out, submit the lead. The unit of success is a completed task. This is the layer with a direct revenue mapping, and the layer where the failures are silent: no rankings dashboard shows you the agent that found you, chose you, and then died on your checkout form.
Visibility gets you into the consideration set. Operability gets you paid.
How the three fit together
They're sequential, not competing. SEO and AEO fill the top of the machine funnel; AXO converts it. The practical implication for a growth team: your SEO stack tells you about rankings, your AEO tooling tells you about citations, and you need a third measurement — task completion, tested with real agent behavior — to know whether any of that attention can become a transaction. Measure all three steps, but fix the deepest broken one first. It's usually the last.