SEO vs AEO: why Google rankings aren't enough anymore

There's a uncomfortable truth that many SEO professionals are still coming to terms with: a website can rank number one on Google for its most important keywords and still be completely invisible to AI search engines. It's not a hypothetical — it's happening right now across thousands of businesses, and the gap between Google visibility and AI visibility is only widening.

The numbers tell the story. AI-powered search tools are growing at an extraordinary pace. Perplexity processes hundreds of millions of queries monthly. ChatGPT's search functionality has become a primary research tool for millions of users. Google's own AI Overviews now appear on a significant percentage of search results, often pushing traditional organic links below the fold. Analysts estimate that by 2027, a third or more of all search interactions will involve AI-generated synthesis rather than traditional link-based results. Businesses that only optimise for traditional rankings are optimising for a shrinking share of how people discover information.

The core reason Google rankings don't automatically translate to AI citations is that these systems evaluate content differently. Google's algorithm is primarily about relevance and authority at the page level — it ranks individual URLs against each other. AI search engines, by contrast, synthesise information across multiple sources to construct an answer. They're not asking "which page is most relevant?" but rather "which brands and facts should I include in my answer?" This is a fundamentally different question, and it favours different signals: content clarity, structured data, cross-source consistency, and the breadth of your online presence matter as much as — or more than — your position in Google's index.

Consider a practical example. A SaaS company ranks first on Google for "best CRM for small business." But when a user asks Perplexity the same question, the AI answer mentions three competitors and omits the Google leader entirely. Why? Because the competitors had better structured comparison content, more detailed schema markup, stronger presence on review aggregators, and content that was formatted in a way the LLM could easily extract and synthesise. The Google-first company had optimised for click-through from a results page; the competitors had optimised for citation within an answer.

The solution isn't to abandon SEO — far from it. SEO remains the foundation that AEO is built on. Strong technical health, quality content, and authoritative backlinks benefit both channels. But businesses need to add an AEO layer to their strategy: auditing AI visibility alongside Google visibility, optimising content structure for LLM extraction, strengthening third-party presence, and implementing schema markup that gives AI crawlers rich context. The first step is simply knowing where you stand. Tools like Casa's AEO analyser give businesses a clear, quantified picture of their AI search visibility — an AEO score that sits alongside their Google rankings as a core metric to track and improve.