What is the difference in a 1LT, 2LT and a 3LT corvette?

What is the difference in a 1LT, 2LT and a 3LT corvette?

The IDs refer to different engines. But they usually come packaged with other options, as well. Just google them and find out the different engines and all the options that come with each.

The 1LT provides you with a quiet interior, quality speakers and comfortable seating, while the 2LT gives you major safety upgrades, convenience enhancements and heating features. The 3LT gives you added luxury with even more comfortable seats and attractive features.

Does that mean it's one or the other or does it include more as you go up? Like 1LT gives you A,B and C and 2LT gives you A,B, and C plus X,Y and Z?