This answer is what is valid in NJ. A criminal defense attorney in NC can provide you with more complete information. The crime of sexual assault can be charged not only with disparity of age (in NJ 3 years) but also based on the relationship between the man and the woman. If the man (or woman) has a teacher-student relationship, interfamilial, employer or employee, counselor-- counselee etc. etc. then the man is subject to charges of criminal sexual assault.
Mr. Sarno is licensed to practice law in NJ and NY. His response here is not legal advice and does not create an attorney/ client relationship. The response is in the form of legal education and is intended to provide general information about the matter in question. Many times the questioner may leave out details which would make the reply unsuitable. Mr. Sarno strongly advises the questioner to confer with an attorney in their own state to acquire more information.
The first answer is mostly correct. The age of consent in North Carolina is 16. I do not know why you would care what New Jersey law says. However, there are exceptions, many of which have been noted.
One thing that is not addressed, however, is the UCMJ. If the 18 year old is in the military or otherwise subject to the UCMJ, 16 is likely insufficient.