What can breast milk supply that other milk cant?

Breast milk contains more iron,and of vitamins c,d and e,compared to cows milk:and minerals and protein are easier to digest from breast milk than they are from cows milk.

and

Breast milk provides the Mom's antibodies to her baby. If you want the cow's protection against some virus, try cow milk -- but viruses are ususally aimed pretty specifically for a species. I don't fret about my body being invaded by cow viruses.