Burst fire:
Requires ammunition.
Deals good damage.
Chance to hit friendly characters when firing over their backs.
Burst fire is used by cool guys.
Aimed fire:
High damage, one shot out of ten when a critical hit occurs.
Low ammunition consumption.
Accuracy.
Being a show-off.
Also, only the Boar eats a lot of ammunition; the rest of the weapons use a normal amount.