Although the terms may be used interchangeably, detergents and soaps are not always the same.

Chart Summary

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Definition

Soaps are compounds of natural oils and fats combined with sodium hydroxide or another strong base. Soaps are surfactants commonly used in the home for washing, bathing, and housekeeping. Soaps are employed in industry as thickeners, components of certain lubricants, and precursors to catalysts. Coloring and perfumes are also typically added chemicals in mainstream, leading-brand soap.

A detergent is a surfactant or combination with cleaning capabilities in dilute solutions. A typical class of detergents includes alkylbenzene sulfonates. Soap-like compounds are more soluble in hard water because the polar sulfonate (of detergents) is less likely to bind to calcium and other ions found in hard water than the polar carboxylate (of soap).

Soap vs. Detergents

As previously stated, there is a chemical difference between soap formulae and detergent formulations. The benefit of laundry detergents over soap is that they are particularly made to operate in washing machine conditions. Some are even formulated to work in special HE (high efficiency) washing machines.
On the other hand, many soaps are meant to clean the skin, hands, or face and are less powerful than detergents. Furthermore, as previously noted, using soap to wash clothes may cause buildup in both the garments and the machine. In other words, detergents are more effective than soaps at removing greasy or oily buildup from surfaces or clothing due to their chemical composition.

Soap is biodegradable and less toxic to the environment than conventional detergents. However, minerals in the water react with soap, turning clothing grey and leaving a film or residue.