Summary:
1.Heifers do not have calves unlike cows that have already delivered calves.
2.Heifers are generally past the weaning stage and are below three years of age while cows are more mature agewise.
3.Cows have very developed udders (with teats) for milk production. Heifers do not seem to have udders.
4.Cows have more prominent vulvas as compared to those of the heifers.