Straight: If your pipework is coming up from the ground, then straight radiator valves are used.
Angled: If your pipework is coming from the wall at an angle, angled valves are used.
TRV: Thermostatic Radiator Valves (TRVs) have an in-built temperature sensor, that keeps the room temperature at a constant level.
Manual: Manual valves are effectively the same as taps – you turn the valve to control the temperature of the room.