The essential element in the global valve is a sphere with holes in the middle. It's in the fully open position and sphere turn 90 degrees to switch to the fully closed position. Ball valves are used in a very open and close or above the desired location quickly closed off.

Advantages, less the pressure loss, easy opening and closing, to be the best of the seal is to be lightweight and small footprint.

seal; as sealing tightness of the ball and the shaft it consists of two stages.