Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, such as the Philippines.
Insular area
An insular area of the United States is a U.S. territory that is neither a part of one of the 50 states nor of a Federal district. of the United States Constitution grants to United States Congress the responsibility of overseeing these territories, of which there are currently 14—three in the Caribbean Sea and 11 in the Pacific Ocean. These territories are classified by whether they are incorporated (by Congress extending the full body of the Constitution to the territory as it applies to the several states), and whether they have an organized territorial government established by the U.S. Congress through an Organic Act. All territories but one are unincorporated, and all but four are considered to be unorganized. Five U.S. territories have a permanent, nonmilitary population. Each of them has a civilian government, a constitution, and enjoys some degree of local political autonomy.