One is tryouts for the other; it's one group. If you do well on corralling the unruly idiots, getting them to show up when and where they're supposed to, making sure they destroy the right buildings and hurt the right people you get promoted to the community group level.
Sincere leftists have a religion they can follow that gives structure to this - their dispute resolution mechanism is to defer to the more leftist person - and the organizers are quite willing to let people take actions that they feel comfortable with - for now (escalating later)