No, not the band. I'm talking about the concept. How exactly does a boy become a man? What makes the difference between man and boy? And where does "guy" fit in the spectrum? If you ask me, there is one big thing that answers all of these questions. It's all about the heart.
When a boy is just a boy, he's just learning. He loves his mother and it's ok that he does. Sure, he probably won't admit it to his friends, nor will he admit his crush on a girl. A guy starts to accept that he can have feelings, he just might not show them. A man accepts and embraces the fact that a woman can be a part of his life. A man doesn't care if he's called a man. A man doesn't care what his image is, although he tries to make a good one. A guy is selective in who he shares his relationship with. A guy is over the "cooties" scare, and although he may admit less to loving his mother than a boy would, but a guy is at least closer to being on his way to manhood than a boy. Not that a man can't still learn, because he can. Everyone can. But when a man loves someone, he doesn't care who knows it. He treats a woman right and is there for her, and lets her be there for him. So the bottom line, when a man's heart is fully opened is when he really is a man.
That is all.