Well there is no difference. Gang A is quite full at the moment, but me and Jade decided that you should all have a choice since we decided on having Rival Gangs.

Gang B is in need of more characters, and I already have one of my characters in there (Who will be joined with another so that I'm not looking like I'm leaning in favour of one Gang xD). But if you wish to join Gang A, you have the option to do so (Though We will probably close Gang A off after that)