I have used android auto and car play in the same vehicle, and car play seems noticably worse.
The top of mind issues I've seen:
Car play requires unlock when the phone is reattached via USB. With android auto, I can simply reconnect after initial configuration.
Music playback stutters fairly often when streaming spotify.
Car play and the iphone more often get into a state where the phone is connected physically but the phone "isn't connected"
I thought this was just me. I used to use Android Auto on the same car I have now, and never had this issue. Got a iPhone some year/s ago and sometimes this happens, maybe once every month or so, but thought the issue was my car or the phone itself. Good to know it happens to others.
I don't think this is true. CarPlay still covers my entire display (which I use for navigation/GPS normally) when someone calls. How this pass any sort of QA/user testing is beyond me. At least Android Auto displays a little message about it, rather than covering the entire display together with the navigation.