The Class B is built on the same frame and uses the same engine as a passenger van. Class B indicates a conversion or camper van instead of a Class A, which is similar to a tour bus, and Class C that is midsize.
A Class B is easy to drive, park and is better on gas than a larger Class A or Class C. It can be parked anyplace a van can be parked.
Class Bs are not designed for a large group of people. Most are designed to sleep two comfortably in beds and up to four rather cozily. Extra passengers sleep on a foldout couch. Larger classes of motor homes will sleep up to 10.
Most have a roof extension for more headroom. Some of the roofs are regular van roofs or some are like pop-up camper roofs.
Class B motor homes offer the same basics as a larger motor home, just on a smaller scale. You could easily compare a Class B to a studio apartment--one space serving as a small kitchenette, living room and bedroom. There is even a small toilet cupboard so you do not have you use public restrooms.