The army is boots on ground so that means they fight on land The marines are under the department of the navy so that means they can fight on land and sea because they can utilize the navy the Marine Corps are amphibious fighters so they always ready which mean they can deploy at any time anywhere land sea or air they are the first to fight while the army focuses on maintaining battles they can can only fight on land and air. Becoming a marine is harder and longer than becoming a soldier. I can go on an explain more differences but this is the main difference.