Arteries carry blood away from the heart, whereas veins carry blood back towards the heart.Arteries have much thicker muscular walls in comparison to veins, as they need to carry blood at high pressure from the heart to the rest of the body. Veins have much thinner walls but therefore, have a much wider lumen in comparison to arteries. (I would draw this in a simple diagram to compare the differences).Veins also have valves to prevent the backflow of blood, which arteries do not have.