I have played games where if you shoot someone in the head twice, it kills em. (With a garand), yet in the limbs, it takes 3 shots. I may be wrong (enemy has low health), but it does seem easier to kill people by shooting them in the head.
From what I can tell the location damage does exist.
The hit points for each location is probably lower for gameplay purposes.
The realism types could easily make a mod or tweak that would make the hit points more intense.
I was asking 2015 to add a realism option in a future patch where it would make the hitpoints harder - perhaps just make it a command line setting for server admins.
But even if that doesn't happen, it would be a simple mod to make say a Torso shot more deadly than a lower leg shot, etc.