The civil war is also called "war between states" why?

Because it was literally a "war between the states" the war took place between the Confederate States of America(almost all of the southern US states) & the United States of America

Well, the country was a unified, separated north and south, fought a war and then was united again. So the whole war was against people living in what was once the United States of America and remains today thanks to Lincoln not allowing the North to back-down to the needs of the south. This is a civil war, a war fought between the people of the same nation with different wants. There is nothing civilized about any war except maybe that soldiers wear clothing. A civil war is a war is a fight against our own people. One place separated by two beliefs leads to a fight between them or a "war between states."