Well This can actuly be becuse of the two dwarf brothers(Sons of the dwarf king Ivalde) that made the hammer in norse myt made the handle to short for Thor
So that now you have to buy TWO different hammers if you want a complete set for your collection. It's bloody GENIUS!
Lol....I knew there was a reasonable answer
Case closed
Different director, different art dept, different movie.
Point taken, but that's outside the Marvel world. Inside that world, how do you justify Mjolnir being changed? We can understand the costume changing, but the hammer?
They explain why they change it in this awesome video, they talk about the hammer at about 6:15 minutes in, but watch it all as its a great look at the props,
D23 Presents Armchair Archivist: Avengers Edition! - YouTube