Obviously, i understand what PvE, co-op, and normal are, but what is the difference between RPG and Normal. Can you travel between realms or is that only with co-op.
RPG Servers are Role Playing Servers. There are additional rules that you must follow to play on the server. It's a lot of fun if you like roleplaying. However if you don't want to be stuck talking in character most of the time then I would suggest that you go to a normal server.
An example would be in the RPG servers people should not be using "lewt speak" or talking in appreviations (i.e. saying TY instead of thank you or talking about current events. Your name should be in character as well.)
Normal means non-role playing and no extra rules(you can read the rules on the Camelot Herald)
Only on the co-op can you travel between realms. On all the other servers the only time you'll see people from other realms is in the frontiers and they won't be friendly