Original: It was the first full-length cel-animated feature in motion picture history, as well as the first animated feature film produced in America, the first produced in full color, the first to be produced by Walt Disney, and the first to be considered a Walt Disney Animated ClassicSmith, Dave.
Simplified: It was the first movie length animated movie to be produced by Walt Disney, the first color movie-length animated movie with sound, and the first American animated feature movie in movie history.