Very Important Foreword
To make a long story short: Worlds Beyond is the best alliance in the whole universe... only newbies don't know that. This page explains what the other alliances are good for.
Alliances: All for one, one for .... erm.... what was that again?
To form an alliance is somewhat nice. You are not alone in the universe anymore. Others will fight at your side for the Good Purpose TM .
Everyone is different, and so is every alliance. You're probably best off with joining an alliance of people that you like. You can leave them at a later point in time, only some alliances don't like that too much.
Often more experienced alliance members will help newbies with:
There are more differences
In terms of gameplay, alliances don't change too much: