Ok, this forum help topic defines the differences between newbie, and nOOb.
A newbie is someone new to something, and is NORMALLY not used to insult someone, but if people are flamers, they'll use anything to their advantage... Including words that normally aren't used for flaming.
Now, nOOb on the other hand... It's a word used to insult people. It usually means that that person thinks they're better than you, that you're annoying, stupid, and more. It's a derivation of the word newbie, used by people in online games usually, when they think they're better than you at it. It actually goes hand in hand with 1337, for that's part of what it was made with, and the people on one side think they're 1337, or "elite". But, all it succeeds in doing is getting people upset.
Usually, when people are called n00bs, they're doing nothing wrong, and people just randomly do it, and that starts the people flaming, but that will be covered in a later topic.
Example: "OMG, your a nOOb." "You're so stupid and annoying, nOOb."
... I have nothing else, if there's anything to add, admins, feel free to add it
EDIT: Changed the title so people better understand it.
~Ab-Z