The butterfly valve is a circular plate with or without an "O" ring for stopping/opening the liquid flow. It is used where the liquid pressure is low and allows less leakage. They are used only for water lines or for non-hazardous liquids at low pressure in closed circuit systems.
Control valves are used in applications where process parameters such as pressure, Tempe It's temperature, volume, velocity (differential pressure), etc., need to be controlled/measured in process lines, reactors or vessels. The characteristics of the control valve are well defined. It is also associated with a pressure/temperature or flow (differential pressure) transmitter connected to an orifice. They also have an actuator and valve positioning adjustment control valve. Sometimes even very accurate instruments, such as differential pressure transmitters using Coriolis measurement speeds and other similar instruments. You should contact an instrument engineer or read a book for better knowledge.