The nutritional advantages of breast milk are certainly numerous. The amino acids in breast milk, the building blocks of proteins, are well balanced for the human baby, as are the sugars (primarily lactose) and fats. The baby's intestinal tract is best aided in its digestion by the vitamins, enzymes, and minerals found in breast milk.
We know that breastfeeding clearly has benefits for the baby. Breast milk is easier to digest and triggers less allergies than infant formula. It contains the mother's infection-fighting antibodies that help protect the baby from a number of common childhood diseases. Breastfeeding may cut the risk of sudden infant death syndrome (SIDS). An indisputable advantage for breastfeeding is it is free; which is a claim that cannot be made for infant formula.
For more information, please see the MedicineNet.com Breastfeeding and Formula Feeding Center.