What is the difference between cattle and oxen?

Greetings,
I am new to cattle and oxen. I was actually doing some initial research on oxen and I'm slowly coming to the realization that "oxen" (so-called), are actually nothing more than just "cattle". Is this true? Maybe somebody with a lot more experience working with oxen and cattle can enlighten me. I was originally interested in possibly using oxen as a draft animal.
Thank you

"Cattle" are "the domesticated animals/species in the Bos genus".

Oxen are cattle that have been trained as draft animals. Oxen are usually castrated males.

Sorry for the ignorance but why do they have to be castrated? As I said, I'm new to all this stuff....

Oxen are typically castrated males because they are more reliably available for draft because they don't get amorous, moody, or pregnant.

Bulls tend to have raging hormones and to be vicious and dangerous. Both cows and bulls are liable to become amorous and then run off with your equipment still attached.

Steers tend to be mild-mannered and not interested in love making. They're still big and can harm you, but less likely to do it intentionally.