What's the difference between colostrum, foremilk and hind milk?

Colostrum usually comes in 1-3 days after birth if its not already present. It is thick and yellowish in colour (because of the high level of Bata-carotene). Colostrum is low in fat and high in protein. It also contains essential vitamins, nutrients and antibodies for building up a newborn’s immunity and protect them after birth (because the baby has been in a totally sterile environment in the mother’s womb). Colostrum also acts as a mild laxative for the baby, this would help to pass the meconium (a thick black, almost tar-like substance which one sees when they baby have his/her first few bowel movements). As a mother continues to breastfeed, colostrum will be present for around two weeks but the mother will start producing more mature milk (which is lower protein but higher in fat and carbohydrate). Foremilk is simply the milk that is first drawn during a feeding. It is generally watery/thin. It tends to be low in fat and high in carbohydrate. Hindmilk is the milk which follows foremilk during a feeding. It is creamier and higher in fat content. The high fat and calorie content of this milk is important for your baby's health and continuing growth. Therefore, it is generally recommended to let a baby drain one breast before moving on to the other. This will help ensure that he/she is getting both foremilk and hindmilk.

This chart is a good explanation on the difference between the three

this may help as well: