A hovercraft (air-cushion vehicle, ACV) is a craft capable of traveling over surfaces while supported by a cushion of slow moving, high-pressure air which is ejected against the surface below and contained within a "skirt." Although supported by air, a hovercraft is not considered an aircraft.
Hovercrafts are used throughout the world as specialized transports. They can also be used after a natural disaster for emergency purposes. Because they are supported by a cushion of air, hovercraft are unique among all other forms of ground transportation in their ability to travel equally well over land, ice, and water. Small hovercraft are used for sport or passenger service, while giant hovercraft have civilian and military applications, and are used to transport cars, tanks, and large equipment in hostile environments and terrain.

A hovercar is a transport vehicle appearing in works of fiction. It is used for personal transportation in the same way a modern automobile is employed. You must steer it, like you would a normal vehicle. The only difference is the "flying" effect.
It is capable of flying and elevates itself some distance from the ground through some repulsion technology, presumably exploiting some short range anti-gravity principle so as to eliminate most friction forces which act against conventional vehicles. Unlike an air cushion vehicle, this does not produce a dust cloud.
Another similar real-world device is the hovercraft, which elevates itself above a water or level hard surface using a cushion of air retained by a flexible skirt. Such devices are not considered to be hover cars, however—that term is used only for the fictional device. Examples of hover cars can be found in science fiction films or television series such as Blade Runner and Back to the Future Part II, and in futuristic racingvideo games, such as the F-Zero series, and the wipEout series.