Size has nothing to do with it:
- A: there is no van or pickup body parts visible. It comes to the RV manufacturer as just a frame and drivetrain (maybe a drivers seat) and the RV manufacturer builds the entire body. (Bus conversions also fall under A).
- B: The front is from a van (or occasionally pickup) but there is no bed over the front. There may be a small amount of storage in the overhead but much smaller.
- C: The front is from a van (or occasionally pickup) and there is a bed over the front.
B+, super C, etc...marketing terms that are undefined.
