ORV or off-road vehicle is a vehicle which is capable of driving on and off paved or gravel surface. It is  generally characterized by having large tires with deep, open treads and a  flexible suspension, or even caterpillar tracks. "All-Terrain Vehicle" or ATV is used  to describe small, open, motorized buggies and tricycles designed for off-road use. It is intended for use by a single operator.  Engine sizes range from 49cc to  950cc.