But which one?
I've just about been trained to use the correct one by now but why the need for any confusion?! The image below is from signing in to my Apple ID info page at Apple.com.
What it is asking for is the password I might need to unlock my iMac not anything that has to do with my Apple ID.
I can only assume that Apple knows this is my iMac or at least that it has access to my iMac's password. Via KeyChain? Who knows. Perhaps a hidden file somewhere in the iMac's dark halls of RAM...
Seems to me I remember Apple asking for my Apple ID password and making that clear by showing that ID in the dialog. That made it obvious which password was needed. Does Apple think making that less obvious, simple, easy is enhancing security?