Don't be silly Citizen and Natural Born Citizen mean exactly the same thing, just like boy and girl mean the same thing. </s>
A Citizen at Birth is a subset of all Citizens. And a “natural born Citizen” is a subset of all Citizens at Birth.
See the Euler Diagram link that follows below. Citizen at Birth under naturalization law Section 1401 and the 14th Amendment are made Citizens of the United States, not a “natural born Citizen” of the United States. The adjectives “natural born” do not appear in the 14th Amendment or Section 1401 of the naturalization law. Adjectives mean something. Natural refers to “natural law” not man-made laws or amendments or treaties. Of tree and plants — all trees are plants but not all plants are tree. See this Euler Diagram to prove the truth or fallacy of the argument regarding the various sets/kinds of citizens and further education: https://cdrkerchner.wordpress.com/tag/euler-diagram/
Some people go through life completely unaware of what is going on around you. You can believe that NBC is self evident, and have fun with that. Good luck.