There several different types of donkeys found in Australia today.
The smallest is the Mediterranean miniature. There are the shaggy, small English/Irish.
The most numerous are the Australian donkey, that are catagorised in to two sizes, standard and large standard.
The Mammoth is the largest type.
There are also many part bred mixes of the various types, so there is a donkey for everyone and every use.
The ADSA register size catagories:
Miniatures - up to and including 9 hands (36")
Standard - over 9 hands and up to and including 11.2 hands
Large Standard - over 11.2 hands and up to 14 hands
Mammoth - Jacks; 14 hands and over
Jennies: 13.2 hands and over
Hybrids - Mules and Hinnies
Mule - mother is a horse and their father is a donkey.
Hinny - mother is a donkey and their father is a horse (rarer than mules)
A male mule is called a John.
A female mule is called a Molly.
Mules are hybrids; they have 63 chromosomes, while the donkey has 62 and the horse 64 chromosomes.
You can breed a mule for any purpose the same as you would a horse; it could be a draft mule, a quarter horse mule or a pony mule depending on the function required.