Castile Soap vs. Goat’s Milk Soap: What You Need to Know Have you ever wondered which soap is better? Castile or goat's milk soap? The truth is they are both great. Soap is soap, right? Well, the answer is both yes and no. The reason is that castile soap is made from saponified oil of plants while goat’s milk soap is made from saponified oils from goats ’milk. In this blog, we’ll take a look at both of these soaps and how they differ.