The term "recreational vehicle" or RV usually calls to mind a motorhome, perhaps a Winnebago brand specifically. It's a large vehicle in which the living space and the driver's seat are all part of the same structure, rather than having the "car" part towing the "living" part.
But recreational vehicles come in many other shapes and sizes, too, and are still properly called RVs. Which one you buy depends on your needs.
The motorhome (commonly called a Winnebago even when it's actually a different brand) is convenient because it offers reasonable living quarters, including a place to sleep, prepare food and use the bathroom. The driver is not disconnected from his passengers; they're in the "back seat," as the living quarters are right behind him. Many people, especially retirees, live in motorhomes full-time, touring the country and enjoying their mobile lifestyle. RV parks have sprouted up all over the country, offering traveling recreational vehicle enthusiasts a place to stop and rest, hook up to electrical posts, and even use the Internet.
Other recreational vehicles are better suited to temporary arrangements, not full-time living. The most basic kind of RV is a simple truck camper, where a shell is attached to the bed of a pickup truck. This is usually for day or weekend trips, with supplies in the covered bed of the truck. The shell can serve the same purpose as a tent would (protection and warmth), making it useful for outdoor camping, too.
Also common is the "fifth wheel," a trailer that attaches to a pickup or medium-duty truck and is hauled that way. A fifth wheel is similar to a motorhome, except that the living quarters are separate from the vehicle. This means the driver cannot communicate directly with people in the trailer unless it's by walkie-talkie or cell phone. Fifth wheels are generally not as comfortable as motorhomes, either, as hence are most useful for relatively short road trips and sightseeing.