long ton (simply ton in countries such as the United Kingdom which formerly used the Imperial system of weights and measures) is a weight ton or gross ton, and is 2,240 pounds (exactly 1,016.0469088 kg)
short ton (usually called simply ton in North America or sometimes called a net ton) = 2,000 lb (about 907.18474 kg).
Both the long ton and the short ton are composed of twenty hundredweights, each having different values for the hundredweight (112 and 100 pounds respectively)
(From wiki)