Natural soap is often overlooked by many for cheaper prices & often because it just is not as accessible as a lot of the commercial soaps. There are three main ways in which commercial & natural soap tend to differ. The first way is in preservatives, then in fragrances, & lastly production.
It is no secret that many commercial soaps contain extra ingredients, these ingredients tend to cause skin issues such as (irritation, dryness, etc). These ingredients are typically added to extend to the life of the soap bar, & to reduce the overall costs of the soap. Natural soap tends to have either no preservatives or use preservatives that are better for your skin.
In fragrances natural soaps tend to either be unscented or use essential oils & natural ingredients as exfoliants. Whereas commercial soap relies on harsh dyes, & various chemicals to create scents in their soap. There are many people that are allergic to the scents in the commercial soap. For the natural soap, the fragrances tend to help the soap bar exfoliate the skin, retain moisture, get rid of excess oils or etc. depending on the fragrances used in the soap.
The last difference is in the way the soaps are produced. Natural soap tends to be handmade in small batches & in many ways is an art that creates natural variations between each soap bar. This form of production takes painstaking attention to detail in balancing the ratios of lye to oil & with the fragrances. In commercial soap making the batches tend to be larger and are pre-formulated to reduce variations and give a standardized bar.