You are largely correct, but the only real part of the chassis that changed was the center tub
to facilitate easier entry/exit for all those that whined about the wider than average sills in the first gen. The actual sub-frames for front and rear and other suspension components remain essentially identical. Even the coil-overs are still bilstien, but use different rebound and compression rates to deal with the different weight distribution driven by a new engine.
The biggest driver of most of the new part numbers were the obvious exterior panel changes as well as essentially an entirely new interior. Then there's the silly stuff like upgraded brake rotors (actually new), new calipers that aren't really new (they just are no longer produce with "Lotus" and instead use off the shelf "AP" products
), wheels, mesh inserts, etc. When you take all of the preceding, it adds up to a lot of new part numbers, but the core car is essentially the same.