Military

Seal Team 6 is equal to 1st Detachment Delta (Delta Force). These two teams have WAY WAY more training then both the Marines and the average grunt. The Marines and Rangers are basically Riflemen, with the fact that if Special Force guys need extra man power they can draw on the Rangers (who have more training then the average grunt) to aid in a mission if they are nearby. To put it in terms everybody can get on D-Day 1944, Seal Team 6 would be the guys that parachuted in the night before to take highly value targets, the Marines would storm the beachs and create a foot (or toe, whichever you prefer) hold, with the Rangers being the major pushing/driving force in pushing the Germans back to Germany.