What is the difference between an Ox and a Bull?

Ox(en) is a sub-genus of Cattle where as Bull is simply the male form of cattle.

What is the difference between an Ox and a Bull?

Oxen are generally castrated cattle used to pull carts or plows. Bulls, obviously, are not castrated.

Oxen are cattle that are trained for draft purposes, and are generally castrated males, preferably horned, not polled (or hornless). They are not steers because they have been castrated after reaching puberty. Oxen can also be any type or gender that are trained for pulling carts, plows, wagons, etc.

Bulls are intact males that are raised for and used for breeding cows and heifers. They are half the cow herd, and generally one bull can be used to breed 25 to 50 cows in a breeding season.