All clans are a little different, and a guild is basically the same thing as a clan. Anyway, some clans are a group of friends playing together, some only accept the best players, and some focus on role playing. The benefit is you have people you can play in team games that you have played with before (and hopefully you know they won't get booted). Clans can also add fun to the game in different ways like ranks or custom ladders. Anyway, hopefully that helps you.
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