I am using one polaroid back made from Hasselblad. I really do not know what it is 80 or something else. But by result of both (polaroid picture) it can not be a big difference. The image is the same size, and Polaroid or Fuji packs are same shape. Construction might be identical, only commercial name it is not.
They take different kinds of Polaroid film. 100 is the newer kind. The back in production, PolaPlus, takes these types of instant film:
Type 665, 667, 668, 669, 679, PC Pro 100 and Pola Pan.
Type 80 backs are discontinued.
I don't think so, but I don't know much.
Considering the state of Polaroid, maybe you should focus on the most recent back as for one it will be easier to find film even if type 80 still exists.
There are (were) two types of backs, one for the focal plane shutters, one to destroy the focal plane shutters. The latter should have a red sticker, but if you have a focal plane blad it is best to be careful before mating a back from some where else...