A surfactant, or surface-active agent, is an ionic chemical that reduces surface tension in water, allowing it to better spread out. Surfactants are useful in cleaning because they emulsify and loosen soil.
Soap is made of natural fat and lye. Its pH level is between 9 and 10, meaning it is alkaline. This makes it an effective cleaning agent.
Detergent is made from petroleum products. It contains many preservatives and antibacterial agents, which do not have an agreeable smell. As a result, detergents usually contain heavy perfumes to counteract the odor.
Soap requires very little energy in production and its ingredients are biodegradable. Detergent is made of toxic, synthetic materials that can harm the environment. Therefore, most environmentally conscious people choose to use soap rather than detergent.
Many beauty products marketed as soap are actually detergents. The chemicals in detergent often cause allergic reactions. They also can contain a harmful preservative called parabens, a chemical that has recently been associated with cancerous tumors.