The carotid artery and the jugular vein are both important blood vessels in the circulatory system. Although they are commonly confused in popular literature and in the media, the two have very different locations and functions. Because of their different functions, they also differ structurally, with each displaying characteristics indicative of its role in the circulatory system.
Arteries are the circulatory system blood vessels responsible for carrying newly oxygenated blood from the heart throughout the rest of the body. This is the blood that has been returned to the heart from the body, pumped from the heart to the lungs, then returned to the heart in preparation to be pumped to the rest of the body. Since the pressure of the blood in arteries is much higher than that in the veins, arteries have more muscular walls than veins.
Veins are the circulatory system blood vessels that return blood from the body to the heart. This is blood that has been deoxygenated and will be pumped through the heart to the lungs. In the lungs, it is then oxygenated and pumped back throughout the body to replenish cells and tissues with the oxygen needed for metabolic functions. One of the main differences between veins and arteries is that veins have valves that keep blood that is moving upward from the lower limbs to the heart from flowing backwards. Another difference between veins and arteries is the dark-blue appearance of veins.
The carotid artery is the large artery that delivers newly oxygenated blood from the heart to the head and neck. There are actually two branches of the carotid artery--a left and a right half, both of which branch directly off of the aorta, the artery that delivers blood directly out of the heart.
The jugular vein can be divided into two sets of veins--the internal and external jugular veins. Both are responsible for transferring deoxygenated blood from the head back towards the heart. The blood from the jugular veins drain into the superior vena cava which transports all the deoxygenated blood from the upper portion of the body to the right atrium of the heart. From there, it will be pumped to the lungs, then back out to the body.
In a number of movies and television shows, the jugular vein is what is thought to be severed when someone's throat is cut in a murder or scene of violence. Since the vein is actually farther back in the throat region than the carotid artery and the jugular vein contains blood under much less pressure than that of the carotid artery, it would be more accurate to say the carotid artery was the blood vessel damaged in these scenes. Blood would spray out of the carotid artery, but not the jugular vein.