What’s the difference between Artisan hand-crafted soap and Commercial brand-name soap I buy at the store?
There are many differences depending on the brands you buy. Some brands are better than others, but it really is answered by comparing how the soap feels on your skin after using it. For most people, commercial soaps leave the skin feeling dry. Others may feel itchy, or find a powder is left behind. Hand-crafted soaps leave your skin feeling moisturized, or like you have used a skin cream or moisturizer.
One of the byproducts of the saponification process is glycerin. Glycerin has many uses outside of soap and therefore many manufacturers will extract it from the soap and sell it or use it to produce moisturizers and creams. Sun Island Body Care leaves the glycerin in the soap. This makes the bar softer and is much better for your skin.
Some commercial soap manufacturers will use man-made ingredients, or chemicals in place of, or in addition to natural ingredients. Chemical based soaps are called detergents.
For more information about the merits of hand-crafted soap versus commercial soap, check out this PDF document titled "Why Handcrafted Soap?" produced by the Handcrafted Soapmakers Guild. You will need Adobe Acrobat Reader to open this document.