Answer: Well, lets think about it they both have common ancestry . Two common things you can take is you can ask yourself what different parts one has and what one does not have to find the answer. for any more help let me know!
Explanation: Have a great day :)
Red blood cells are disc shaped. It is thought one factor that allows them to have this shape is because they do not have a nucleus. This tends to increase amount of space inside the cell for hemoglobin.
They have a flexible disc shape which helps increase the surface- to- area volume ratio which enables oxygen and carbon dioxide to diffuse across the red blood cell's plasma membrane more readily.
Their disc shape also enables them to squeeze through tiny capillaries that are half their size .