I think you would have to look at the ingredients on the package.
If you are popping the corn yourself and adding butter it would have a lot of saturated fat.... according to how much butter you use.
If you are using a powdered cheese seasoning, it would be more likely to have some vegetable oil ( Corn, Soybean, or Sunflower Oil), and some chemical additives for stabilization etc. like Disodium Phosphate.
Normally, I think buttered would be more caloric, but it depends on the specific ingredients in the cheese flavoring.