What’s the difference between a 2,000-calorie diet that contains sugary, fatty foods and a 2,000-calorie diet that is well-balanced in carbohydrates, fats, and proteins

With one that contains sugary, fat foods, you're still getting your caloric intake, but it's made of very little nutrients, and that allows your body to store more fat and endanger your health. A diet with carbs, fats, proteins allows your body to get the most out of what your eating.
Hope this helps!

Dialect is probably part of the answer