| Blood Plasma | Serum |
| Nature. It is the fluid part of blood. | It is the fluid that comes out of a contracting blood clot. |
| Colour. Blood plasma is of yellow colour. | Serum is nearly colourless. |
| Turbidity. It is turbid or cloudy | Turbidity is absent. |
| Fibrinogen. It is present in the blood plasma. | It is absent in serum. |
| Prothrombin. It contains prothrombin. | Prothrombin is absent. |
| Clotting. It can clot. | It is a consequence of clotting. |