That's a big difference from the one that I mentioned. The 720 is 45 W vs 18 W. In addition, it is a quad core vs a dual core, but I'm sure that someone as vastly intelligent as you already knew that off the top of your head.
Dual cores run hot, too, not as much, obviously but even relatively idle the 720QM is very warm. Like I said, why do you think Newegg is giving away free cooling pads?