what are soaps and detergents and what are synthetic detergents

Soaps are salts of naturally occurring fatty acids. They are formed by treating animal fats with sodium hydroxide, known as caustic lye. A typical soap molecule has two parts: a long non-polar tail of carbon and hydrogen atoms and a polar head containing at least one ionic bond. The molecule has a long hydrocarbon tail that allows it to dissolve grease, and a polar head that is water soluble. These fats are broken down by microbes hence they are biodegradable.

Usually all detergents are synthetic.

Chemists began developing a class of synthetic soap like compounds known as detergents, which offer several advantageous over true soaps such as stronger grease penetration and lower price. Detergents are like soap molecules where both possess a polar head attached to a non polar tail.

The polar head in a detergent molecule, generally consists of either a sulfate group, , or a sulfonate group, ,  which has many advantages over soaps such as stronger grease penetration and lower price. Detergents are very much soluble in hard water compared to soaps as their polar sulfonate groups (called surfactants), less likely bind to calcium or other ions in hard water and will not form any film compared to soaps.

But detergents are synthetic compounds (sulphate salts of carboxylic acids) which cannot be broken down by organisms, and hence are non-biodegradable and cause water pollution.