According to Leo Donofrio, the framers drew a distinction between the meaning of “citizen” and the meaning of “natural born citizen”. A “citizen” can be Senator or Representative, but in order to be President one must be a natural born citizen.
It's the difference between a fact and a legal status.
Whether you are a natural born citizen is a fact of nature which can't be waived or renounced, but your actual legal citizenship can be renounced. The difference is subtle, but so very important. “Natural born citizen” is not a different form of “citizenship”.
It is a manner of acquiring citizenship. And while natural born citizens may end their legal tie to the country by renouncing citizenship, they will always have been naturally born into that nation as a citizen. \ 212. Citizens and natives. (from Vattel's book) The citizens are the members of the civil society; bound to this society by certain duties, and subject to its authority, they equally participate in its advantages. The natives, or natural-born citizens, are those born in the country, of parents who are citizens. Two different sentences. Two different civil groups are being discussed. “As the society cannot exist and perpetuate itself otherwise than by the children of the citizens, those children naturally follow the condition of their fathers, and succeed to all their rights…I say, that, in order to be of the country, it is necessary that a person be born of a father who is a citizen; for, if he is born there of a foreigner, it will be only the place of his birth, and not his country.