There are lots of differences, but the most important has to do with glycerin.  Glycerin is what gives soap its “slip” and moisture.  It’s the element in professional shaving soaps that make that lather result in a good shave.

Commercial soap companies extract the natural glycerin from their soap and sell it to lotion companies, or use it in their own lotion products if they have them.  That’s why commercial soaps are so drying.

Handmade soap retains all its natural glycerin content, so it’s never drying.  Because I use only handmade soap, my need for lotion has diminished dramatically, and I haven’t purchased shaving cream since I tested my first handmade bar.

The other differences are pretty obvious…commercial soap uses synthetic chemicals for lather, fragrance, and handmade soaps are very often all-natural or even entirely organic.

Ours are usually 100% organic, with the exception of a few natural fragrance oils which I will occasionally use instead of an organic essential oil.  Mine are also always vegan.  No animal products.

Those are the major differences.  Isn’t soap educational?