they are real ! first, the babies that don’t have full hats that cover their entire head have a little hair above their ears and at the back of their head. and some of the ones you got are old series that are not produced anymore that’s why they look so different. sonny angels changed their design in 2016, so all collections before that point have a slightly different design.
The ones produced & sold in other countries (ex: Hong Kong) also use a diff mold! So they might look a little different hehe. But you’re right! It can also be from an older, unrefined series!
You prob already figured this out but all the Sonny’s you got are real! :p Some are just unrefined (meaning older) so they just have different features compared to the newer series. Just a little different but equally as cute. :)