What is the difference between arteries and veins, and arterial blood from venous?

Arteries are vessels that extend from the heart and carry oxygen-rich blood to various organs and tissues of the body. Veins are such vessels that carry blood containing carbon dioxide from the organs into the pulmonary alveoli, where it leaves it (then it is excreted through the lungs into the environment), and the used oxygen-free blood elements are saturated with oxygen that has entered the body during respiration. Then this new, enriched blood falls into the heart, and in the process of its contractions, it is carried throughout the body by arteries of different calibers and nourishes organs and tissues again.