Differences between models with same floorplan?

Stick and tin construction is heavier than fiberglass laminated walls, but easier to repair. The "lite" designation generally means made with lighter weight materials, i.e. foam sandwich floors, lighter frames, etc. which may or may not be as durable as a heavier construction method. Cargo capacity of the TT is another thing to keep an eye on. Watch for axles and tires that are barely adequate for the anticipated load you will put in the trailer.