You have 2 different blood vessels inside your body that circulate the blood.
#1 is the arteries,the vessels that have a "pulse" these vessels carry oxygenated blood throughout your body,under pressure,that's what is called the "blood pressure".That blood is bright "cardinal" red,from the oxygen percent.
#2 are the veins,they carry blood back to the heart and lungs so the blood can exchange carbon dioxide for oxygen,we breath this by- product out of our body when we exhale the air in our lungs.
These vessels carry the darker blood is a dark "reddish purple" color,because the oxygen depletion,the "veins" also do not "pulse" because its not under allot of pressure etc.
You don't have "blue" blood,that's a very old term that was used to describe sick babies with heart defects etc.