They aren’t exactly the same. Google’s sign in shares your email address and “basic profile info,” e.g., your name. You may then be asked for a number of additional permissions. Apple’s lets you choose what name to give to the developer, if they even ask, and gives you the option to use an Apple relay email if you don’t want to give your email. You won’t be asked for more permissions. Apple also says they don’t track the apps you use or your activity and their terms forbid the developer from associating your relay email with other email addresses; Google has very clear privacy policy requirements but does track.
Given that, I wouldn’t say this is a mere Rorschach test.