In practice, if not in theory, I think Android works the same way. Yes, there are other app stores, and yes you can install untrusted, but in practice, most people just use the Play Store (requiring a Google account) and if they allow untrusted or use another app store, it's not the default.

I'm not arguing Apple and Google are the same, far from, but in this area, they seem the same to me for the majority of the population. (Android user)