Plasma is a component of blood, with a clotting factor called fibrinogen.
Serum is that part of the blood that is devoid of it. This basically happens whrn the components of blood are separated.
Blood serum is mostly water that is dissolved with proteins, hormones, minerals and carbon dioxide. It is a very important source of electrolytes.
Plasma is a clear and yellowish fluid part of the blood. It is also found in lymph or in intramuscular fluids. This is the part of the blood that contains fibrin and other clotting factors. Plasma makes up about 55% of the total blood volume. The main constituent of blood plasma is water.