What is the special thing about Xavi and Iniesta?

Ok I constantly read that they are masters of the ping game and both possess extraordinary vision. To an average soccer fan like me, a good p is a p that reaches your target man and a great p is one which unlocks a defense but it seems that there are tons of players out there with such attributes so what makes this two players so special that they are icons now when talk about exquisite ping abilities. I would like to have a better understanding of the beautiful game.