According to Wikipedia the meaning of a donkey and mule.
In its common modern meaning, a mule is the offspring of a male donkey and a female horse. The reverse, the offspring of a male horse and a female donkey, is called a hinny. The term "mule" (Latin mulus) was formerly applied to the offspring of any two creatures of different species – in modern usage, a "hybrid".The mule, easier to breed and usually larger in size than a hinny, has monopolised the attention of breeders. The chromosome match-up more often occurs when the jack (male donkey) is the sire and the mare (female horse) is the dam. Sometimes people let a stallion (male horse) run with a jenny (female donkey) for as long as six years before getting her pregnant. Mules and hinnies are almost always sterile (see fertile mules below for rare cases) (see External links). The sterility is attributed to the different number of chromosomes the two species have: donkeys have 62 chromosomes, while horses have 64. Their offspring thus have 63 chromosomes which cannot evenly divide. A female mule, called a "molly", that has estrus cycles and can carry a fetus, can occasionally occur naturally as well as through embryo transfer. The difficulty is in getting the molly pregnant in the first place.
The donkey or ass Equus asinus, is a domesticated animal of the horse family, Equidae.Most wild donkeys are between 102 cm (10 hands) and 142 cm (14 hands) in length. Domestic donkeys stand under 91 cm (9 hands) to over 142 cm (over 14 hands) tall. The Andalucian-Cordobesan breed of southern Spain can reach up to 16 hands high. Donkeys are adapted to marginal desert lands, and have many traits that are unique to the species as a result. They need less food than horses. Overfed donkeys can suffer from a disease called laminitis. Unlike horse fur, donkey fur is not waterproof, and so they must have shelter when it rains. Wild donkeys live separated from each other, unlike tight wild horse herds. Donkeys have developed very loud voices, which can be heard for over three kilometers, to keep in contact with other donkeys of their herd over the wide spaces of the desert. Donkeys have larger ears than horses to hear the distant calls of fellow donkeys, and to help cool the donkey's blood. Donkeys' tough digestive system can break down inedible vegetation and extract moisture from food more efficiently. Donkeys can defend themselves with a powerful kick of their hind legs.
