ram air vs. CAI
Yes, there is a difference. a true "ram air" system does exactly that; takes air from outside the engine bay and, due to forward motion of the vehicle, forces air into the intake. Nothing like a supercharger though. The faster you go, the higher the pressure inside the ram scoop, and more O2 into the intake. You have to be moving to see any appreciable gains.
a Cold Air Intake, like the K&N 64 I have on mine, isn't a true CAI either; none of them really are unless the intake is outside the engine bay. What you do get is a better breathing intake system that removes the inherant restriction of homolgated production vehicles (all for one, one for all concept in build design). With a CAI system, your engine can take in a larger volume of air, but it comes from within the engine bay, so the air is somewhat heated by the warm engine. However, the volume of air is much greater than that of a stock system, which when combined with more fuel, offers more combustion mix, and a stronger combustion pulse.
I'm very pleased with my CAI, the SOTP acceleration is noticable right out of the box. Stronger pull throughout the rev range too. I've haven't noticed any MPG gains yet; can't seem to stop burying the loud pedal!