What is the difference in structure and function between and artery and vein?

Arteries carry blood away from the heart, e.g aorta and pulmonary artery, arteries are thick, the inside of them is made of epithelial cells as they are smooth, they help blood flow more easily, the middle layer is muscle, these can go along with pulses to help them. the outside is made of elastic tissue, this enables it to withstand high pressures. veins have valves in them to stop backflow of blood, they all carry deoxygenated blood apart from the pulmonary vein, they have less elastic tissue in them than arteries.
Pulmonary Arteries lead from the heart to the lungs. Systemic arteries go everywhere else. Consequently, the pulmonary arteries are usually slightly smaller and thinner. There is also less of them.
Arteries carry blood away from the heart. Veins carry blood toward the heart.
Veins have a "check valve" that prevents the blood from going the wrong direction in our body. 1. Wall of vein is much thinner in diameter as compared to those of artery. 2. The vein has a thin fibrous layer whereas artery has much thicker inextensible fibrous layer.