Human or frog blood can carry more oxygen per unit of time and why?

Red blood cells in human blood are different from red blood cells in frog blood. The main difference is the presence of a nucleus in frog erythrocytes. They have a convex shape. They are also much larger compared to humans. In humans, erythrocytes are biconcave and small in size. Although in a frog, red blood cells are larger and, accordingly, can carry more oxygen, but in humans, there are about thirteen times more red blood cells in the blood. Due to this, human blood is able to carry much more oxygen than frog blood.