Serum is the colorless and transparent liquid that precipitates on the surface of the blood clot after the blood has clotted. The differences between serum and plasma are: i. Different colors. Plasma is pale yellow, and serum is colorless and transparent. Second, the specific gravity is different, the specific gravity of plasma is greater than the specific gravity of serum. Third, the internal components are not the same. Plasma contains albumin, globulin, and various coagulation factors; while serum does not contain various coagulation factors, but only albumin, globulin, and various inorganic ions. Fourth, the clinical roles of serum and plasma are not the same. Since plasma contains various coagulation factors, it is said that it is often used clinically for various coagulation disorders, such as hemophilia A, hemophilia B, vascular hemophilia, etc.; because serum does not contain various coagulation factors, it cannot be used for various coagulation disorders, but serum also contains various antibodies, which can be used for patients with low immunity.