What is meant by the 'circulation systems' in terms of blood flow?

There are two circulatory systems in the body that enable blood to flow around the body. One system is between the heart and the lungs, and the other is from the heart to every other part of the body. The heart pumps deoxygenated blood to the lungs, where it gains oxygen, before returning to the heart. This oxygenated blood is then pumped to the rest of the body to supply the body with oxygen.