Web app is faster, has more features, easier to use. Copilot key is useless, it took me a while to figure out how to get it to open the M365 app, instead of the corporate blocked personal one, and then I used it zero times. Never think to use it and I found it has no practical purpose, except Microsoft marketing.

Interesting. It prompted me to install the microsoft store version which, when launched manually is identical to the web version. As the keyboard key brought up a web window telling me to install it, I assumed it just launched that.