The return of blood to the heart is assisted by the action of the skeletal- muscle pump. As muscles move, they squeeze the veins running through them. Veins contain a series of one-way valves, and they are squeezed, blood is pushed through the valves, which then close to prevent backflow.
Answer: Veins are the pathways for blood to go back to the heart, arteries are under pressure actively moving blood. Since veins aren't under the pressure to move blood, they have one-way valves to keep blood going the right direction. They are also made of smooth muscle to help move blood as well as skeletal muscle around the veins.
