As I understand it, Arca Swiss is the standard that came from the camera world, and is still hugely popular today for shooting (like the RRS stuff)
Arca Trax (Arca Lok, etc) is a modular rail system that adds notches on the sides to mitigate against recoil, I suppose. RRS uses a set screw system to achieve the same thing.
Arca 3 way is a plate that has Arca, picatinny, and a Harris bipod attachment in one piece.