Yes, the OEM setup pulls cold air from the front of the radiator just like the NW CAI does, but there are 2 differences :
1. The air has already passed through the filter and now has a straight shot to the throttle body with the CAI.
2. The CAI is not acting like a big ole heat sink sitting on top of the engine, the IAT's are much lower at the IAT/MAF sensor just before the throttle body resulting in a denser air charge to the combustion chambers.
( and 3. it looks cool - I hate the later years trend of covering up engines with plastic goo-gaw )