A freight car used to haul bulk materials such as coal, fertilizer, or grain which can be unloaded by opening doors on the bottom of the car. Covered Hoppers have a roof with loading hatches to protect the load. Typical hoppers can carry 100 tons of coal, or 3,500 bushels of corn.

An open-top car for hauling items that don't need protection like coal and gravel. Unloaded through doors in funnel-like bins in bottom of car. Covered hoppers have roofs; carry grain and other items that need protection from weather.

A hopper car is a type of railroad freight car used to transport loose bulk commodities such as coal, ore, grain, track ballast, and the like.