There would always be a difference in nutritional values as consumed versus as sold; the reason it varies between nutrients is because nutrients react differently during the cooking process. The calories would also increase due to the presence of oil in the product.
When food is cooked, it loses water content which increases it's density and, therefore, will causes the calorie value to increase slightly. Cooking wouldn't have an effect on protein content which is why that doesn't change, but it does affect the fibre content, which in turn will increase carb value.