Arteries and veins both carry blood in the body, but are very different in terms of their composition and functions. Both arteries and veins are important components of the circulatory system, carrying blood between the heart, lungs and other parts of the body.
The major difference between arteries and veins is their directional flow. Arteries carry mostly oxygenated blood from the heart to the different body parts. Veins carry mostly de-oxygenated blood to the heart from the other body parts.
For efficiency in delivering oxygenated blood all over the body, arteries are made out of a special kind of tissue. Arterial tissue has an outer layer of connective tissue covering the middle layer which is made up of muscular tissue. The muscular tissue contract in between heart beats. This contraction is what is measured as a pulse. In effect it is the arterial muscle tissue contracting, not the heart beat. The next layer of the arteries is made up of smooth specialized endothelial cells. The smoothness allows the blood to flow through. When this is damaged, strokes and heart attacks can occur.
Vein tissues are similar to arterial tissue, the main difference being that the muscular tissue in veins does not contract. Without blood in them, veins collapse. From the different body parts, the veins carry blood filled with carbon dioxide to the lungs. When the blood is oxygenated there, they continue with it into the heart, then the heart pumps out the blood again through the arteries.