Earn more points and get a higher "difference" score to unlock higher ranks and 
their corresponding bonuses:

  Corporal: 30 points, 30 difference; can create Squad option. 
  Sergeant: 100 point, 70 difference; can create Clan option. 
  Sergeant 1st Class: 200 points, 100 difference; unlocks Shotgun and SMG. 
  Master Sergeant: 350 points, 150 difference; unlocks Medic Badge. 
  Sergeant Major: 550 points, 250 difference; unlocks HGH and ISA LMG. 
  Lieutenant: 880 points, 250 difference; unlocks Engineer Badge. 
  Captain: 1,100 points, 300 difference; unlocks VC9 missile launcher. 
  Major: 1,450 points, 350 difference; unlocks Tactician Badge. 
  Colonel: 2,300 points, 450 difference; unlocks Saboteur Badge. 
  General: 2,800 points, 500 difference; unlocks Scout Badge. 
  Lieutenant-Colonel: 1,850 points, 400 difference; unlocks grenade launcher.