> Lactose is a disaccharide composed of galactose and glucose and has the molecular formula C₁₂H₂₂O₁₁.

What could be different?

Do you mean that relative amount of lactose? I believe it's that's not different in the raw material.[0]

[0] https://www.canr.msu.edu/news/goat-milk-versus-cow-milk-a-co...