Vital means PM's with person 1 and person 2 between server 1 and server 2.
m21 means (or does he?) whispering between player 1 and player 2 in speficic area. Example: Player 1 is in beach. Player 2 is sitting next to him.
Player 1 sends: /w omg lolz!
Player 2 (and everyone in speficic area) receives: Whisper from Player 1: omg lolz!
BUT.. If Player 1 is at beach and Player 2 is at Grove Street.
Player 1 sends: /w omg lolz 2!
Player 2 receives nothing because he is not in the whisper range.
This could be done in some RPG servers with SDK.. It would easier the playing experience for not all shouting to everyone while talking. Like messagemode would be set to "Talk", wich would have been defined to be in longer range than whisper, but shorter range than shouting for example. And of course, ooc as shoutout to whole server.