The short hood contains ancillary equipment, frequently a chemical-retention toilet for crew use, and may contain a steam generator for heating older-style passenger cars.
Originally, this was not the case; railroads preferred to have the long hood leading, for additional crew protection in a collision, and because it was the familiar mode of operating steam locomotives.
Many older locomotives were modified to have a low short hood and were referred to as chop-nosed.
More recently, it has become the standard for the locomotive's nose to be built full-width, instead of having a narrow short hood.
Some single cab designs did have American-style short and long hoods (known as "bonnets" in Britain).