The concepts of water starch and corn starch are different.

Water starch is starch mixed with water, while corn starch is dry starch made from corn. In other words, corn starch can also become water starch by adding water. Generally, water starch is used in making soup.

Starches used for cooking mainly include mung bean starch, potato starch, wheat starch, water chestnut and lotus root starch, etc. Starch is insoluble in water and gelatinizes into a colloidal solution when heated to 60C with water. Thickening takes advantage of this property of starch. The starch used to thicken gravy, also called dough, is a polysaccharide polymer formed by the condensation of multiple glucose molecules.