Microsoft describes Copilot as “your everyday AI companion,” a phrase that sounds like marketing until you notice what it implies about distribution. Copilot is not just a chatbot you visit. It is threaded through Windows, Edge, Office, and Bing, sitting inside tools hundreds of millions of people already open every day. That reach is the reason the ChatGPT vs Microsoft Copilot comparison matters at all. But reach is not the interesting part. The interesting part is that these two engines, which look like competitors, are drinking from substantially the same well when they decide who to cite, and that shared plumbing changes how you should think about earning a mention from either.
Most brands treat every AI engine as a separate optimization target and exhaust themselves chasing each one. With ChatGPT and Copilot, that instinct wastes effort, because a large part of what earns a citation in one earns it in the other. The trick is knowing exactly where they overlap and where the small but real differences live.
The Bing-shared spine
Here is the structural fact that governs this comparison: both engines lean on Bing. Copilot grounds its answers in Bing’s index directly, retrieving pages Bing surfaces and citing them with visible footnotes. ChatGPT’s search capability has deep Bing roots as well, even as OpenAI has added its own retrieval. I call this the Bing-shared spine, and it is why these two engines so often cite the same pages for the same questions.
The practical consequence is large and mostly overlooked. Your Bing visibility, the thing most brands neglect entirely because they pour everything into Google, is a direct input to whether both Copilot and ChatGPT cite you. A page that Bing understands, trusts, and ranks is a page positioned to be retrieved by both engines that sit on top of Bing. This means one underused lever, Bing search health, quietly moves your standing in two AI engines at once. Brands that have optimized only for Google have a real blind spot here, because the search engine they ignored is the one feeding the AI answers they now care about.
Why Copilot rewards Bing health so directly
Copilot is the more transparent of the two about its dependence on Bing, and that transparency is useful because it tells you exactly what to fix. When Copilot answers a question, it runs a Bing search, pulls the pages Bing considers relevant and trustworthy, and cites them plainly. If you want to be cited by Copilot, the most direct path is to be a page Bing surfaces well for the questions your buyers ask.
That makes Bing optimization the surprisingly concrete starting move for Copilot AEO. Make sure Bing can crawl your site cleanly, that your pages are indexed, and that they are structured to answer the specific questions clearly. Bing and Google reward similar fundamentals, so a well-built page usually does fine in both, but many brands have never checked their Bing presence at all and are invisible there through simple neglect rather than any real disadvantage. Fixing that neglect is often the fastest Copilot win available, because you are not building new authority so much as claiming visibility in an index you had ignored. Copilot then inherits that visibility and cites you, footnote and all.
Where ChatGPT diverges
If the engines shared everything, this would be a one-move article. They do not, and the divergence is worth understanding so you do not assume Copilot success automatically transfers. ChatGPT increasingly uses its own retrieval alongside its Bing lineage, and a large share of its answers come from the model’s training rather than any live search at all. That gives it a second path to mentioning your brand that Copilot leans on less: what the model absorbed about you during training.
So ChatGPT rewards two things Copilot weights differently. It rewards the same searchable, Bing-friendly clarity that Copilot needs, and it rewards broad presence in the kind of authoritative, widely-referenced content that shapes what a model learns during training. Copilot, being more search-grounded, cares most about the first. This is why a brand can be cited well by Copilot through strong Bing presence yet still be underrepresented in ChatGPT’s training-based answers, or the reverse, cited by ChatGPT from training while thin in Bing and therefore quiet in Copilot. The engines overlap on the search spine and diverge on the training path, and knowing which gap you have tells you which lever to pull.
What to build for both
The honest strategy here is efficient, because the overlap is so large. Build one well-structured, authoritative asset and both engines can cite it. Start with search health across both Bing and Google, since the Bing-shared spine makes Bing visibility unusually valuable for these two engines specifically. Then add the legibility that every AI engine rewards: direct answers near the top, clear structure, thorough coverage of the specific question, and clean crawlability so the retrieval can actually read you.
At Instant Press we measure this combined readiness with the AEO rating, and a page that scores well tends to satisfy the shared spine and the divergent paths at once, because the qualities it measures, clarity, structure, authority, and technical access, are exactly what both a Bing-grounded engine and a training-shaped engine reward. The one addition worth making specifically for this pair is a deliberate Bing check, because it is the highest-value neglected lever and it moves both engines. Confirm Bing indexes you, confirm your pages answer the real questions cleanly, and you have positioned yourself for the two engines that share Bing’s spine. Then keep producing the broad, authoritative content that feeds ChatGPT’s training path, and you cover the divergence too. So which one cites your brand? Whichever one you fed. Feed the shared spine through Bing health and both will, and the brand that finally stops ignoring Bing usually finds it was the cheapest AI visibility it never bought.