What is the difference between vitamin d milk and whole milk?

The federal Food and Drug Administration (FDA) establishes standards for different types of milk and milk products. Some states use these standards, while others have their own standards. Prior to 1998, the federal standards required that fluid milk sold as whole milk must have no less than 3.25% milk fat, low-fat milk must have 0.5-2.0% milk fat, and SKIM milk must have less than 0.5% milk fat. Starting in 1998, the FDA required that milk with 2% milk fat must be labeled as "reduced-fat" because it did not meet the new definition of low-fat products as having less than 3 grams of fat per serving. Milk with 1% milk fat could still be labeled as "low-fat" because it did meet the definition. Vitamin D concentrate may be added to milk in the amount of 400 international units (IU) per quart. Most low fat and skim milk also has 2,000 IU of Vitamin A added.