ATVs are four-wheel, utility vehicles generally used to transport large heavy items. They can also be used for personal lumbering and hunting purposes.
Quads can be used for racing or for recreational purposes as well as for work purposes such as farming or landscaping.
ATVs are capable of enabling people to enjoy a tough ride, with their passengers able to alter the weight distribution in the vehicle to improve grip or steering.
ATVs have lower clearance and take more energy from the rider to ride. There's not much space inside, but they can do a lot of tasks a quad can't.