Arteries carry oxygenated blood away from the heart and typically have high blood pressure. Veins carry deoxygenated blood to the heart and typically have low blood pressure. This is the reason behind the 120/80 - 140/90 mmHg blood pressure that is seen during the measurement of the blood pressure. Arteries have blood in high pressure and large quantity as the heart pushes the blood away from it to the various organs. Veins carry the blood away from the organs due to the pull of the heart, this creates a low pressure zone inside the veins.