The Chevrolet site will show you the difference. I know because we've been looking. We've opted for the LT2 over the LT1, but alot of dealer's DON'T recognize (or even realize!) there is a difference, from what I've found.
Here's the link to the comparison page:
The LT2 pretty much has everything offered on the LT1, or better. In addition:
the LT2 has a power remote liftgate, rearview camera is integrated into rearview mirror (awesome feature if you haven't seen it), TRI-zone climate controls (as opposed to just dual), second row captains chairs are standard, but if you want 8 passenger seating then it's bench (it's opposite on the LT1), Nav system is available, sunroof is available, power passenger seat is available, leather appointed seats are available, premium sound system is standard, Electrochromic, Automatic-dimming Rearview Mirror is standard.
Hope that helps!