Helpy/Gallery

So, as shown in the FNaF 4 Minigame we see their are multiple suits:

And yes, the sprites could have just changed but I also do have a theory:

Fredbear's animatronic sprite doesn't change at all, unless you count the cutouts and such but y'know, those are cutouts, not the animatronic.

But as shown in the same minigame there are a lot of different sprites for Spring Bonnie:

Now, I think it is safe to assume which suit is Springtrap, or the one that William wears:

And how small his head is, it's kinda of like the one on stage:

And possibly in that fire like popcorn, his head popped and turned humongous or something.

And since Afton keeps these suits it wouldn't be surprising if he kept the suits too, and since Afton is smart if he lost on suit he could use another. So, maybe he used one of these suits which have a bigger head:

And it would just be reasonable because of how oh lighter Scraptrap is then Springtrap:

And shown by these sprites one is brighter then the other:

So that would be a fun idea.

But there could be another idea, like Scrapbaby who remade herself, maybe since Scraptrap took other aniamtronics and metals and made them look more like Spring Bonnie / Springtrap, I mean, that's an Alchemist I guess, and he is shown to be a technician so it wouldn't be that big of a surprise.

But, there is probably the most likely answer!

It's just how Scott models probably, he probably made such an change because he probably wanted it to look different from the Afton in FNaF 3, which worked but to people's eyes it matters if it was good or not.

But there is probably no lore reason to this, I mostly did this for fun to see some other options, nothing serious.

So yes, it's probably just a way Scott models and probably to make it look more different from Springtrap from FNaF 3, for better or worse, you can decide.

But that's what I think, just Scott's modeling.