There are three general types of Ball Valves:
Full port: This has an over sized ball so that the hole in the ball is of the same size as the pipeline thereby resulting in lower friction loss. The valve is larger and the flow is unrestricted.
Standard port: This has a smaller ball and hence a smaller port. This is less expensive. Flow through this type of Butterfly Valve is one pipe size smaller than the valve's pipe size which results in slightly restricted flow.
Reduced port: Here the flow through the valve is two pipe sizes smaller than the valve's pipe size which also results in restricted flow.

More products of valves

Globe Valves

Safety valves

Plug Valves

Reducing Valves

Balance Valves