I can be not right, but I think that citizen is the person who lives in America and has citizenship and national is the person whose parents are Americans. (Sorry for mistakes)

Are you a citizen or national of America? This is the question you are sometimes asked by customs officials when you enter the U.S. All U.S. citizens are U.S. nationals, but not all U.S. nationals are U.S. citizens. A U.S. national owes his allegiance to the United States. Nationals include citizens and people born in certain outlying possessions such as Samoa. If you are a citizen of American Samoa, or are the child of a citizen of American Samoa, then you are a national but not a citizen of America.

Sorry to the others, but they are wrong responses. A citizen is born in the US or has earned it through the naturalization process. A national is someone who was born in territory owned by the US, such as previously the Philippines, Guam, Puerto Rico, and the Virgin Islands. Nationals, who are not citizens, cannot vote or hold elected office positions. But they can live and work in the United States without restrictions and apply for citizenship. However as of 2005, nationals are now limited to American Samoa and Swains Island because the Philippines are now independent and those born in Guam, PR, and the Virgin Islands have full citizenship.

citizen=vatandaş national=milliyet

citizen is the one who live in the country , national the one who is born there but not living it