First there was the wild ass, way before the donkey, mule, burro, and jackass.
A relative of the zebra, the African ass became a beast of human burdens thousands of years ago.
This domesticated ass is what we came to call a donkey. It quickly spread to Europe and Asia. Burros, often used as pack animals, are just small, surefooted donkeys.
A male ass or donkey is called a jack (hence, “jackass”), and a female is called a jennet or a jenny.
If a jack donkey is mated with a female horse, the offspring is a mule. A cross between a jenny and a male horse produces a hinny.
Both mules and hinnies are hybrids, which means they can’t reproduce.