TT, Legendary, and whatever else there is

Kisho_Seiko - Heavens Tear

Well, here's a question: what's the difference between them, between the types, in terms of armor, weapons whatnot? I'm starting to reach the level of going into TT and grabbing some of the things to start making them, and I'm just looking for information on them before I start getting into the fray.

Thank you.