What are the differences between arterial and venous thrombosis?

Location and flow : Arteries carry blood, oxygen, and nutrients from the heart to the rest of the body. If an artery thromboses (usually from atherosclerosis) the tissue supplied can die for lack of oxygen. Veins drain blood from the body back to the heart. If a vein thromboses, the greatest risk is of a clot breaking off and traveling to the heart and lungs, where it can block blood flow through the lungs.

Throbosis=clot: A thrombosis is a blood clot. The veins are redundant meaning that there are a lot of them draining a certain area. So a venous thrombosis is usually not really important except for discomfort as long as it is in the surface veins. One in the deep veins is a medical emergency. The arteries are less redundant and a clot in an artery can damage the area it supplies and can be very serious.