1.Arteries-are blood vessels that carry blood away from the heart

arteriols-smallest arteries
aorta-the largest arteries
2.Capillaries-are tiny blood vessels that from a network throughout the bodies organs and tissues
3.Veins-are blood vessel that carry blood back to the heart.

The biggest veins are the superior and the inferior vena cava
There are three types of blood vessels 1st is the artery which carries the blood away from the heart.
2nd is the veins which carries blood back o the heart.
3rd is the capillaries which is the actual changes of gases.
Aorta is the biggest artery of the body while arterioles are the smallest artery in the body.
Superior and inferior vena cavas are the another biggest blood vessel in the body.