Difference between Red and White Blood Cells

In the human body, blood has three major functions: transportation, regulation, and protection. There are three types of cells that make up blood: red blood cells, white blood cells, and platelets. In the following article, we will examine the differences between red and white blood cells.


Red vs White Blood Cells
An image of the red blood cell which is present in a capillary of pancreatic tissue in the human organism

Red blood cells, also known as erythrocytes, are the most abundant type of cells in the human organism. Red blood cells are what is known in biology as anucleated cells (without a nucleus). The space that would have been occupied by the nucleus allows for more pigment known as hemoglobin to be present inside each cell. This pigment is responsible for spreading oxygen around the human organism. Hemoglobin predominantly consists of iron, which, when bound with oxygen, gives blood its red color.

white blood cells
3D rendering of various types of white blood cells found in the human organism

White blood cells, also known as leukocytes, are responsible for immune response of the human organism.

There are five different types of white blood cells that can be generally divided into two main categories:

  1. Granulocytes, which are characterized by visible granules in their cell body.
  2. Eosinophils. These cells are able to release toxins, should infections and parasitic worms enter the human organism. Eosinophils also play the crucial role in the building of inflammatory response to various allergic reactions.
  3. Neutrophils are the most abundant type of white cells in the body. They are responsible for destroying foreign bacteria that invade the human organism. When we are injured or get sick, neutrophils are the first cells which respond to the invasion.
  4. Basophils. These cells produce histamine (which helps fight allergies) and heparin (which is responsible for preventing blood from clotting and sending more blood to the damaged region of the body).
  5. Agranulocytes. Do not have visible granules in their cell body. These are comprised of:
    • Monocytes. The compartments that comprise human blood need to be cleaned constantly. These cells are responsible for that. They are also the largest in number among all the cells.
    • Lymphocytes. These are active agents in formation of the various immune responses, and activate when the organism “notices” the presence of malevolent microorganisms infiltrated inside the human body.

Red blood cells vs White blood cells

  • The main difference between red blood cells and white blood cells is in their respective functions. While red blood cells are responsible for transport of respiratory gases (oxygen and carbon dioxide), white blood cells provide defense mechanisms for fighting foreign microorganisms entering the human organism.
  • The two types have different structures. While red blood cells do not have a nucleus, white blood cells do.

    human blood through a 1000x microscope
    This is what human blood looks like through a 1000x microscope
  • Red blood cells are of a red color, hence their name. The color is made possible due to the presence of hemoglobin. White blood cells, on the other hand, are colorless. Hemoglobin works essentially as a storer of oxygen, which can be further transported to various parts of the body and is responsible for the overall amount of energy an individual has. When people do not have enough red blood cells, they often show symptoms of anemia- the feeling of tiredness.

    white and red blood cells
    A rendering of the white and the red cells, side by side
  • Red blood cells are more populous and have a longer lifespan than white blood cells. The former’s population is around 5 million per cubic millimeter of blood, while the latter are around 3,000 – 7,000 per cubic millimeter of blood.

Comparison chart

Red blood cells White blood cells
Originate in red bone marrow Originate in bone marrow, and also in lymph nodes, spleen
The nucleus is absent in cells Have a nucleus
The size is around 7.5 µm, are smaller The size is around 15 µm, are bigger
Are filled with hemoglobin (Red) Are colorless
Have an average lifespan of 120 days Have a lifespan of from 5 to 21 days
5 million RBCs in every cubic mm of blood 3,000 – 7,000 WBCs in every cubic mm of blood
Number increases during exercise and at high altitudes Number increases during infection
Circular, Biconcave in shape Rounded and Amoeboid, Irregular in shape
Non-Motile Generally motile (having the power to move spontaneously)
Do not leave blood vessels Come out of blood Capillaries
Form stacks or aggregations known as Rouleaux Do not form Rouleaux
Belong to the Cardiovascular system Belong to the Cardiovascular lymphatic systems
Main function: transport of respiratory gases (oxygen and carbon dioxide) Main function: defense mechanisms