Introduction:
The lymph is a clear fluid that circulates throughout the body's lymphatic system. It is derived from the blood plasma and plays a crucial role in the immune system. In comparison to blood, lymph has some distinct differences in its composition.

Comparison between lymph and blood:

1. Cellular components:
- Red blood cells (RBCs): Blood contains a significantly higher number of RBCs compared to lymph. RBCs are responsible for carrying oxygen to the body's tissues and removing carbon dioxide. However, RBCs are not present in lymph.
- White blood cells (WBCs): Lymph has a higher concentration of WBCs compared to blood. WBCs are an essential component of the immune system and help in defending the body against infections and diseases.

2. Plasma:
- Blood plasma: Blood plasma is the liquid component of blood and accounts for about 55% of its total volume. It contains various proteins, electrolytes, hormones, nutrients, and waste products.
- Lymph plasma: Lymph also contains plasma, but it lacks the proteins present in blood plasma. This is because the majority of plasma proteins, such as albumin and globulins, are too large to enter the lymphatic vessels and are retained in the blood.

3. Composition:
- Blood: Blood consists of approximately 45% RBCs, 55% plasma, and a small number of WBCs.
- Lymph: Lymph mainly consists of WBCs, lymphocytes, and a clear fluid derived from blood plasma.

4. Function:
- Blood: Blood performs various functions such as transportation of oxygen, nutrients, hormones, and waste products, regulation of body temperature, pH balance, and protection against infections.
- Lymph: Lymph plays a vital role in the immune system. It transports WBCs, antibodies, and other immune cells to the lymph nodes and other lymphoid tissues, where they help in identifying and eliminating pathogens, foreign substances, and abnormal cells.

Conclusion:
In comparison to blood, lymph has a higher concentration of WBCs and lacks RBCs. It contains plasma derived from blood but lacks the proteins found in blood plasma. Lymph plays a crucial role in the immune system by transporting immune cells and antibodies to fight against infections and diseases.