Blue veins and green veins tend to be things that many people think about because they both show up in our bodies. The main difference between blue and green tissue is the pigmentation. The dark, blue appearance of light is due to the interaction of light with the oxygenated blood in the blue vessels. On the other hand, green veins appear lighter and greener because the underlying skin tone blends with the blue of the veins It is interesting how such small changes can make a distinct visual difference so that we can see it on our skin!