Soap and shampoo are cleaning agent in our daily life. However, why soap is in solid form and shampoo is in a liquid form? Is it because of the chemical compenants inside them or other factor? And which cleaning agent has a high efficentcy on cleaning grease from the body?

Soap and shampoo are both cleaning agents in our daily life.

Why is soap in solid form and shampoo is in a liquid form, though? Is it because of the chemical components inside them or another factor? Which cleaning agent has a higher efficiency in cleaning grease from the body?