If you have spoken to more than one digital marketing agency in the last year, you have probably heard all four of these terms — often used interchangeably, which is part of the problem. They are related, but they are not the same thing, and they do not deserve equal budget at every stage of a business's growth.
Here is the plain-English breakdown, and a framework for deciding where to start.
The four, in one sentence each
SEO (Search Engine Optimisation) gets your website ranking on Google and Bing's results pages. AEO (Answer Engine Optimisation) gets your content pulled directly into featured snippets and Google's AI Overview. GEO (Generative Engine Optimisation) gets your business cited by name inside answers from ChatGPT, Perplexity and Gemini. AAO (Assistive Agent Optimisation) makes your business discoverable and evaluable by autonomous AI agents acting on a customer's behalf, rather than a human typing a search query at all.
How they actually relate to each other
They are not four separate campaigns. They are four different audiences reading the same underlying signal — your website's structure, content, and machine-readable data — and each one asks something slightly different of it.
SEO asks: is this page fast, crawlable, and authoritative enough to rank? AEO asks: is this page structured clearly enough to be lifted into a snippet? GEO asks: is this business a source an AI model trusts enough to cite by name? AAO asks: can an autonomous system read this business's services and contact details without a human explaining it first?
A site with strong technical SEO and clear entity data is already most of the way toward AEO and GEO. AAO is the newest and most forward-looking layer — see our AAO playbook for what that involves in practice.
The decision framework, by stage
Pre-revenue or early-stage: start with SEO
If your website is new, thin on content, or has technical issues, none of the other three will work — AEO and GEO both depend on a technically sound, crawlable foundation. Get the basics right first: fast pages, clean structure, real content that answers real questions. See our SEO playbook.
Established with decent traffic, low conversion visibility in AI tools: add AEO
If your SEO is working — you rank, you get traffic — but you never see your brand mentioned when customers describe using AI to research your category, AEO is the next investment. FAQ schema, direct-answer content structure, and question-shaped headings are the fastest lever here. See our AEO playbook.
B2B, considered-purchase, or competing on expertise: prioritise GEO
If your buyers research extensively before contacting you — professional services, B2B logistics, healthcare, anything with a longer sales cycle — GEO matters more than it does for an impulse-purchase retail brand, because those buyers are increasingly asking ChatGPT or Perplexity to shortlist providers before they ever visit a website. See our GEO playbook.
Forward-looking and technically resourced: layer in AAO
AAO is early. Most businesses do not need it urgently today. But it is inexpensive to implement well (an llms.txt file and clean JSON-LD schema are not large engineering lifts), and the businesses that have it in place before autonomous agent commerce becomes common will be the default answer when those agents look for a provider.
What we would not do
We would not recommend a business with a broken or nonexistent website jump straight to GEO or AAO. The foundation has to be technically sound first — see our Complete Digital Stack playbook for why we treat this as one integrated system rather than four disconnected line items.
We would also be skeptical of any agency that pitches all four as a single undifferentiated bundle without explaining which one is actually solving your current problem. They compound each other, but they are not interchangeable, and the right starting point depends entirely on where your business is today.