What is the difference between a donkey, mule, jack and a burro?

Donkey is one of the common names for Equus asinus. Another is @ss (ridiculous that this site won't allow you to use perfectly legitimate zoological terms). A male donkey is called a jack, and a female is called a jenny - jack therefore simply means a male donkey. 'Burro' is Spanish for donkey. A mule is a hybrid, the offspring of a male donkey and female horse. The offspring of a male horse and female donkey is called a hinny.