Originally Posted by partyjungle
Which is advantageous for who?
What's full mount and side guard?
I really haven't a clue what they are doing once they are on the ground.
Bjj, submission wrestling etc is extremely nuanced, so the following is very general.
Full guard. If you are on your back the best position to be in is the full guard. This allows for some control of your opponents posture and hips. It also allows you to possibly submit or sweep/reverse your position, meaning that you end up on top of posting on your feet.
Half guard. If you have a person in your full guard, that is you on your back, them between your legs, your opponent may try to' guard pass', get past or out of your guard. They may look for side control, where you have no legs around them, and they are lying perpendicular to your body, chest to chest. The may also look for full mount, where they sit straddled on your chest. Both of these positions are bad for the guy on the bottom, so often, during a guard pass, the guy on the bottom will end up retaining one of his opponents legs with both of his own. Again, sweeps and reversals are possible from this position