I tweeted that question. great thanks information! !

In Japanese all they are called Ushi, pronounced like Sushi.
sometimes say male ushi "Oushi". bull is Oushi.

I learned from followers
・Ox is for work. both male and femail but in many cases ox is male. female is said cow.
・Ox is more friendly than Bull.
・Bull is Non-castrated male, more powerful.
・"Bull" is not use for female.