The big difference is the level of model customisation, I think. On G2 Lite you have a choice of two helicopters and can select beginner, intermediate, or advanced. I believe this sets the sensitivity of the model, essentially altering the setup. As I understand it, you can fully adjust various properties of the selected model on the "full" G2.

For me, this wasn't important. As long as there's a heli model that's a reasonable approximation of a .30 and the flight model is good then it will be useful for learning.

Maybe in the future I'll regret the choice, but for the moment I see no advatage of the full version while I'm learning.