𝐀𝐑𝐓𝐄𝐑𝐈𝐄𝐒 carry oxygenated blood away from the heart. They have thick walls with muscle tissue to withstand blood pressure. Its distinct structure allows them to adjust their diameter to maintain blood pressure and to control blood flow.

𝐕𝐄𝐈𝐍𝐒 carry deoxygenated blood towards the heart. They have thinner walls because the pressure in veins is so much lower compared to the arteries. Veins can widen (dilate) as the amount of fluid in them increases. They use valves, particularly the legs in the veins, to keep the blood flowing.

𝐕𝐄𝐍𝐀 𝐂𝐀𝐕𝐀 is the largest vein in the body that transports blood to the heart from other areas of the body. It has two parts namely the superior vena cava and the inferior vena cava. The former carries blood from the head, neck, arms, and chest, while the latter carries blood from the legs, feet, and organs in the abdomen and pelvis.

Sources:
Gupta, J. & Shea, M. (2019). Biology of the Blood Vessels. Retrieved from https://www.msdmanuals.com/home/heart-and-blood-vessel-disorders/biology-of-the-heart-and-blood-vessels/biology-of-the-blood-vessels#v29655131

National Cancer Institute (n.d.) Vena cava. Retrieved from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/vena-cava