AEO vs SEO: what changes when AI answers the question

Search is splitting into two surfaces

A few years ago, ranking on page one meant your link appeared, someone clicked, and you got a visit. That deal still exists, but it is no longer the only game.

Today, a meaningful share of searches end with a direct answer: Google's AI Overview appears above the organic results, ChatGPT returns a sourced paragraph, Perplexity cites three sites and summarises the answer. The user gets what they needed without ever clicking through.

This is the split: blue links (the classic channel) and AI-generated answers (the emerging one). Both matter. Both draw from your site. The question is whether your site is readable enough to be included in either.

What AEO actually is

Answer Engine Optimization gets talked about as if it is a new discipline that replaces SEO. It is not.

AEO is 80% the same SEO fundamentals you should already be doing: fast-loading pages, clean HTML, clear headings, descriptive link text, structured data, a crawlable architecture. If your site scores well on those fundamentals, you are most of the way there for AI answer engines too, because they use the same crawlers and pull from the same content.

Google says as much. Its own AI features optimization guidance is blunt: there is no separate "AEO" for Google — its AI Overviews and AI Mode draw from the regular search index, so the work is simply good SEO. The real divergence shows up across the wider answer-engine ecosystem — ChatGPT, Perplexity, Claude, and AI agents — where conventions and content legibility behave differently. That whole picture is what our guide to getting found by AI search walks through.

The additional 20% is AI-specific signals: the ways that large language models parse and evaluate content that differ slightly from how a classic ranking algorithm does. This is where it gets interesting.

What genuinely changes for AI answer engines

Content must be real text, not images of text. A pricing table embedded as a screenshot, a phone number in a banner image, a product spec inside a PDF with no HTML version: these are invisible to LLM crawlers. If the text cannot be selected and copied in a browser, it is probably not being parsed.

Structure is read, not just ranked. Classic SEO cares that you have an H1. AI answer engines actively use your heading hierarchy to understand what a page is about and which section answers which question. A page with clear ## and ### headings that mirror likely questions performs better than a wall of prose.

Semantic HTML matters more than it did. article, main, section, nav: these tags tell a crawler what content is the main body versus sidebar versus footer. Boilerplate noise in the main content area dilutes the signal.

Parseable product and pricing information. If you sell something, your pricing page should have real text prices, not a comparison table built in a design tool and exported as an image. Schema.org markup (Product, Offer, FAQPage) gives AI engines structured hooks into your data.

llms.txt. An unofficial convention: a plain-text file at yourdomain.com/llms.txt that points AI tools at your key pages. Be clear-eyed about it, though — Google says it does nothing for their AI, and there is little evidence other engines lean on it. It is a low-cost courtesy, not a lever. We make the honest case in full.

A practical checklist

You do not need to rebuild your site. Start here:

• Audit your text. Open every key page and try to select the most important content with your cursor. If you cannot select it, it is probably an image. Fix that first.
• Review your heading structure. Each page should have one H1, logical H2s for major sections, and H3s for sub-points. The headings should read like questions your customer might type.
• Check your pricing and product pages. If the price is only in an image or a styled component that renders as $--, fix it. Add Product and Offer schema markup.
• Add an FAQ block to your highest-traffic pages. AI answer engines love clearly posed questions with direct, contained answers.
• Make sure your content is server-rendered. Most AI crawlers do not run JavaScript — if your text only appears after scripts run, they never see it. (llms.txt, by contrast, is optional at best: here's why.)
• Run a structured data validator. Google's Rich Results Test and schema.org's validator are free. Use them.
• Check Core Web Vitals. Slow pages get deprioritised in both classic search and AI answer engines. Load time is a shared signal.

How this connects to a unified score

The unhelpful thing about having two surfaces to optimise for is that it can feel like double the work. It is not, if you think about it correctly.

Classic SEO and AEO share the same foundation: a site that is fast, clear, well-structured, and technically sound. The differences are at the edges.

This is why we built the Legibility Score in Rankport: a single 0-100 number that covers both. Crawlability, Structure, AI-answer readiness, and Performance are the four sub-scores. A site that does well on all four is well-positioned for both blue links and AI answers. A site that ignores the AI-specific signals is leaving a growing share of visibility on the table.

The audit tells you exactly where the gaps are, in plain English, without requiring you to hold two separate mental models of how search works.

Start with the fundamentals. Extend for AI. Measure both in one place.