Saponification

The process of soap making involves a chemical reaction, called saponification, that converts fat (acid) and lye (base) into soap (salt) and glycerin.

Some commercially made bars are not called soap because they’re actually synthetic detergents with the glycerin removed. The company makes more money by selling the glycerin on its own, I assume to other companies that specialize in extremely large bubbles.

Unlike saponification, emulsification involves a non-chemical process where two or more non-mixable liquids are allowed to be mixed. Milk, vinaigrettes, and mayonnaise all fall into this category. There are different processes, but you can imagine that in an oil and water mixture, the oil surrounds small droplets of water allowing a stabilized suspension.