I tend to use n00b and newbie very differently.
A newbie is someone who's new to the game (or just bad at it, some people are slow learners), and is willing to listen to people who knows the game and gives advice. he'll ask for advice, and maybe even apologize when he doesn something stupid.
A n00b is someone who's also new to, or bad at the game, but with a way to big ego ("seriously guys, my dick is 20" long and i bench-press 200 kg")
If he does something stupid over and over and you try to give him som eadvice he'll usually reply with something along the lines of "STFU n00b fag" or "come to (insert RL place) and i'll fuck you up, lets see how tough you are *****"
I love the last one, can't stop laughign when someone thinks they're tough asking someoen to travel halfway across teh world to fight them.
He gets really angry when he's not tEH pwnzor of the game, he'll teamkill for fun, rage-quit, or start screaming into the mic if theres voice chat.
I know this is just how i use the two words, and many people use either word for both types of new players.
Whats unfortunate is that many people treat both kind of players (whether you wanna call them n00b or newbies) the same, if they screw up, they're yelled at "OMG fucking retarded n00b, do u swallow semen from stupid donkeys for nreakfeast or soemthing" And while this would be fair to the n00bs (my definition) it's pretty hard on the newbies (again, my definition) and it'll turn them into n00bs.