They have valves to keep the blood from backing up. They do not respond to drugs. Veins bring blood tethe heart. They have smooth muscle that can open and shut the vessels. They carry the red, oxygenated blood from the lungs to the body.
Arteries bring blood away from the heart.
They are similar to veins in that they carry unoxygenated blood, however, the vessels are called arteries because they have smooth muscle, react to stimuli and drugs, and carry blood away from the heart to the lungs. These vessels cany oxygenated blood from the lungs to the left heart. They do not contain muscle that reacts to stimuli and medications. Vessels so small that they admit only one cell at a time. These vessels are also reactive to stimuli and are the exchange between arteries and veins both in the lungs and the rest of the body.