Ur boy. The guy who you feel comfortable with, and want to socialize with. He's probably been your friend for a long time, and greeting him as bredda will inform him you like him, and view him as your equal.
A male who, like it or not, is indefinitely your brother and may haze the crap out of you, or love you to death. This male may be a real blood-relative, or may be a friend so close to you that you act like siblings. There are many variations of brothers, but "bruddah" is the best kind, because successfully or not, they try to fix all your problems and buy the world for you even when they're living in a cardboard box. Like every brother, "bruddahs" have their problems with you, but no matter how bad the problem is, they still stick together.