Well, I am not familiar with EQ, but from what I have seen, Planeshift Guilds are far more \"official\" than in other games. Most of the games I have played have these different clans who are just a group of friends who kill things together. In Planeshift, it is a group of friends roleplaying in similar ways, sharing roleplayed beliefs. To be successful, it requires alot of work and cooperation.
The politics in Planeshift are also probably the most complex I have ever seen in a game.