What is the difference between horses, oxen and mules?

[aWagonMaster]

Gery Barker wrote sometime back
"There may be more difference in individual personality than between species. Horses can be very loyal to an owner or driver, but then there are horses that would be happier simply left alone. The horse is probably the easiest to train. They can be worked, especially in harness as young as two. They are multipurpose. But they are temperamental and can be excitable.. Mules ar more self assured. I think they are smarter than a horse in thier own way, but the mule always likes to think that he (or she) is in charge. Mules take a lot of patience to train. Some can kick, although none of mine did once they were trained. Oxen are the most complete herd animal in the world. They are born herd sour. They want everything the same all the time. They are very willing workers. They rely on their humans. For example, if a horse gets caught in a fence, they will fight their way free, possibly hurting themselves in the process. An ox will call for help and wait until the human arives to free him. It is a tremendous responsibility."