I can locate the co-pilot feature in Word but not in OneNote. Additionally, when comparing Word's Co-pilot with ChatGPT 4.0, I find that ChatGPT 4.0 is significantly superior.
You probably use either the Web version of OneNote or the windows 10 version. Copilot is only available in the M365 version. As for the performance, after several testing I have to say it depends on the context, but I do agree that often I prefer the Chat GPT result. It's mainly due to the fact that because Copilot is part of the products there more instructions before your prompt (pre-prompt) that what you'll find in ChatGPT directly. The main advantage for an organization would be the fact that it's available directly in the user applications and that you have control over the deployment, security, analytics etc...
