The vessels which carry blood from heart to other parts of the body are known as arteries. The blood vessels which take blood from body parts to the heart are called veins. Pulmonary arteries carry blood from heart to lungs and Pulmonary veins carry blood back to the heart from lungs. These veins contain blood which flows from lungs to heart so that the blood in pulmonary veins is rich in oxygen. Whereas, the blood present in pulmonary arteries contains less oxygen as compare to the blood in other arteries.