If nothing else about the two different models stands out to you, then for the wheelsets, consider that the CLX III are deeper profile by more the 10mm with the frond being 12mm deeper. So they can be more aero.

Roval makes good wheels. So depending on how aero a wheel you want pick your model bike. Or consider if you can do better buying another brand wheelset that is more aero than the C38 for the $2000 difference.