I've got the liberty, and some of the major differences you'll find between the two are the brakes, gearing, and fit, and componenets, so basically everything
. To start, the gearing on the road bike will be higher in every gear. Your front has a 48/38/28 while the gravity has a 52/42/30. They are both an 8 speed, however, the gravity has a 12-25 cassette vs your 11-32. What that means is that your 7.2 will have a much easier gear than the gravity. The gravity will be faster in any given gear for the same cadence. The brakes on your 7.2 are undoubtedly better than the bargain bin rim brakes thrown on the gravity, just FYI. The wheel set on the gravity is also very basic, but the have stayed tryed for me, though it doesn't get ridden that much. The gravity is a pretty heavy bike too, it's probably right around 26 pounds unloaded.
Other than that, the gravity does what it does well for the price. If you go that route, make sure to have it set up properly - I had to grease pretty much everything that would reqiure it and adjust the hubs, headset, brakes, derailleurs, ect.. If you can't do this yourself it can easily cost $100.00 to have a bike assembled at a shop, something to keep in mind.
If I had to do it over, I would have gotten a few year old used bike. The reason I didn't was because the frame size was unavailable.