The breastmilk from induced lactation is comparable to breastmilk produced by someone roughly ten days after giving birth and breastfeeding. This is known as mature milk.
The hormone placental lactogen is excreted by the placenta. Among its other functions, it is responsible for the production of colostrum from around the 16th week of pregnancy.
Once someone gives birth, the expulsion of the placenta results in a drop in placental lactogen levels. This, in turn, causes breasts to stop producing colostrum and transition to mature milk. Because someone who has not given birth does not experience this process, the milk produced is comparable to the “mature milk” produced after colostrum has ceased.