What is the Difference Between Similar But Different Things, Terms, and Objects

What is the Difference between Veins and Arteries

The circulatory system in the body consists of veins and arteries. Both do the same function of carrying blood from one part of the body to the other but this is the only common thing between them. Otherwise they differ not only in their function but also in nature. Both have to do well to keep the system of the body running efficiently.