What is the size difference between a dolphin and a human?
depends. what kind of dolphin?
There is very little difference between the circulatory system of a horse and a human other than size. The other primary difference would be that the human system functions on a vertical plane and the horse system functions on a more horizontal plane because of the natural orientation of their bodies.
Numerous differences can be seen between frog blood and human blood. Perhaps the most obvious is the oval shape of the frog erythrocytes rather than the biconcave discs of human blood. Moreover, the frog erythrocytes have a nucleus (here stained blue) whilst human erythrocytes do not. There is less difference in size between the erythrocytes and leucocytes than in human blood. There are no platelets in frog blood.