Thanks for the link to that thread Qawsed!
I never understood the plate/leather/chain variants. Can someone elaborate, please?
There's one set of leather and one set of chain.
Plate starts with Iron, steel, elven, dwarven, orcish, etc. and the rest of the materials common to the Elder Scrolls world.
With Plate, ther are 3 models of cuirasses and pauldrons of different style, but with the same armor value.