Enlisted Marine Corps ranks are broken down into three levels, Junior Enlisted, Non-Commissioned Officers, and Staff Non-Commissioned Officers. As a Marine moves up the ladder his or her responsibility and contribution to the mission increases.
Also, children born abroad to two non-citizen nationals or to one alien parent and one non-citizen national parent are eligible for non-citizen national status. This is so rare that the State Department does not even issue a certificate for it. Non-citizen nationals are delineated as such in their passports.
The answer is no. There are people living legally in the United States who are not citizens. If you were born in this country you are a U.S citizen. If your parents are U.S. citizens, but you were born in another country, you are also a U.S. citizen. Citizens enjoy many freedoms and rights.