Both apples and oranges are fruits but apples are usually sweet and oranges are usually citrus.
The calories in apples and oranges comes from carbohydrates(18g-22g), of which 50% is from sugar. The fat and protein content is very negligible in both.
edit Vitamins and Minerals
Oranges are an excellent source of Vitamin C, with nearly 140% of daily intake requirement, whereas apples contain roughly 7%. Oranges also have a greater amt of Vitamin A, 6% as compared to apples at 2%. Potassium is higher in Oranges (300mg) as compared to apples(26mg). Apples have a higher foliage (55mcg) as compared to oranges (23mcg).
Both apples and oranges contain soluble and insoluble fiber, which helps regulate the bowel movements, blood suagr levels and lower cholestrol.Apple roughly has 5 g of fiber whereas orange has 3 g.
edit Health Benefits
Apples are known to have numerous health benefits ranging from preventing Asthma, Alzheimers, Parkinson's disease, certain cancers, gallstones, type2 diabetes and reducing cholesterol, hemorrhoids and help controlling your weight etc. The high soluble fiber, vitamins, minerals and antioxidants help help boost your immune system and fortify your body.
Oranges, due to their excellent source of vitamins, fiber and minerals, also help prevent Asthma, diabetes, Arthritis, certain cancers, kidney stones, high blood pressure and lower cholesterol. Due to it's high acidic content and the presence of antioxidants like Beta-carotene, oranges can protect the skin cells from getting damaged and keep it young and moisturized.