Tech X2 and Race X2 are replacements for old mono/mini. Basically they are the 2 piston, XC suitable brakes (Race model is lighter)
Then you have Tech V2. Again, 2 piston, but with a wider caliper body and able to run twin ply, vented rotors.
Tech M4 are the four pot, beefier versions.
The Tech lever and caliper assemblies are pieces of CNC'd beauty, i've just fitted some Tech X2 with braided hoses and floating rotors, they look the business but can't comment on performance yet as i've been poorly since I fitted them!
Hope that helps