Red blood cells or Erythrocytes
RBCs are the biconcave cells; also known as erythrocytes. RBCs contain the iron-rich protein called haemoglobin; give blood its red colour. RBCs are the most copious blood cell produced in bone marrows. Their main function is to transport oxygen from and to various tissues and organs.
White blood cells or Leucocytes
Leucocytes are the colourless blood cells. They are colourless because it is devoid of haemoglobin. They further classified as granulocytes and agranulocytes. WBCs mainly contribute to immunity and defence mechanism.
Standard ranges of RBCs are male: 4.7 to 6.1 million cells / mcL. Female: 4.2 to 5.4 million cells / mcLThe average number of WBCs in the blood is 4,500 to 11,000 WBC per microliter. Cell ratio in normal human blood is roughly 600 RBCs: 1 WBC.