The top part is the same. Anyway, what I mean to point out is that Steel Masquerade’s armor design seems to have come from the Season 3 character’s armor design (the ponies on the Finalists poster reuse stuff from the show), not the other way around.
Doubt it, that armor looks nothing like what Nayuki designed. Besides, don’t you think MLP has good enough designers to create their own characters and clothing? Just look at Chrysalis and the Royal Guard armor.