Tionese gear is your base lv50 gear which you can get as soon as you hit lv50.
Columi gear can be obtained from doing hard mode flashpoints and story mode operations.
Rakata you get from hard more tier 1 operations and story mode tier 2 operations.
Black Hole you get from black hole comms you get from doing the black hole section of corellia (an endgame daily area) and story mode tier 2 operations. Campaign gear, which is basically the same as black hole gear but with different stat types you get from hard mode explosive conflict (a tier 2 operation).
Dreadguard and Hazmat gear you get from doing hard mode terror from beyond (a tier 2 operation).
All of this gear is primarily for the really tough endgame content, mostly Operations which involve 8 or 16 people playing together... and it's not all that easy to get, it takes a lot of time and effort and a lot of team work from other players.