A pickup truck is a light truck with a bed consisting of an open cargo area, short rigid sides, and a utility gate in the rear that opens. Types and sizes of pickup trucks differ from country to country, but in North America pickup trucks primarily come in full-size (heavier vehicles with a V6 or V8 engine) and compact (lighter, with a V4 or V6 engine). Pickup trucks are used mainly as a work vehicle used for construction or other professions where heavy loads need to be carried, and at a low cost a pickup truck makes a great vehicle to haul around heavy cargo.
There are different types and sizes of pickup trucks such as, the compact pickup, which is what most people think of as a regular pickup. The compact pickup truck is the most common type. It has a two-axle chassis, a sturdy frame, cab with one bench seat, leaf spring suspension on the rear wheels to provide the most stability and strength to varying cargo weights, and a gasoline engine with size of V6 or below.
The next size up is a full-size pickup, which is a larger truck suitable for half-ton cargoes and able to perform other functions, like hauling trailers. You'll find them with either gasoline or diesel engines up to size V10. The largest full-size pickups have two rear tires on either side of the rear axle -- totaling six tires for the truck. These trucks are called "duallys" or dual-wheeled pickup trucks and may be equipped with a fifth wheel to tow heavy trailers.