He has two palette swaps, known as G. Oriber and Wong Who.
All three men are obese, wearing high-cuffed slacks with suspenders over a grandfather shirt. They also wear clog-style shoes and armbands on both arms at the elbow.
Bill Bull (who is of Mexican descent) wears dark gray/forest green pants, is bald and sports an Amish beard; G. Oriber (who is of Arabic descent) is also bald, wears light blue pants and sports a full beard; and Wong Who (who is of Chinese descent) wears green pants, has an Eastern high-tied ponytail and a Fu Manchu moustache.
Bill Bull is 6'5" and weighs 568 lbs.
According to the art book Capcom Design Works - Early Days, Bill Bull (and his palette swaps) are based on a real person, namely a "hard-hitting" old man seen at a restaurant near Capcom's headquarters.
Not much is known about their personalities, but according to Capcom Classics Collection, Bill Bull's favorite drink is a mixture of ketchup, mustard, soy sauce, and salad dressing. A bit concerned about his weight, lately, he has gone on a diet.
All three men share a distinctive attack pattern; they put their heads down and charge at the player headfirst, much like a bull. They have a limited ability to change direction in mid-charge, which makes them difficult to avoid safely. They also have a kick attack, but are otherwise harmless while not running.