There are many different types of design for valve bodies. Depending on the valve body construction, some valve bodies are made from one piece (casted or forged from metal material in one), some valve bodies are made from more than one piece, they may be jointed by bolts or welding etc.
Commonly, single piece body valve has a better performance in leaking proof, Multipieces body designed valves has the design and construction advantage because of the joints.
These types of valve body design are very common in industry valves, especially in the ball valve design.