They are from two very different designers and constructions. The VMA outfit is a Gaultier original that was showcased in his haute couture collection, the Marry The Night outfit was molded specifically for GaGa by a lesser known designer.
I highly doubt it, the Marry The Night dress represents body transformation (here's the evidence: youtube.com/...) and the VMA dress I have no clue hahaha
I can't tell the difference, but where the arrow is pointing, is also where Gaga is putting her left leg in the left picture. Possibly covering up a... mark of some kind. I'm not sure what, though. I might just be dumb. Lol