Generally, there is no difference. If it's in a job posting or job description, my best guess would be that the one labeled as a circulating nurse would more than likely not have an opportunity to learn to scrub. The one labeled as OR nurse may or may not have the opportunity to learn to scrub. Most facilities utilize surgical technologists in the scrub role because they are cheaper. Also, many states have certain requirements that the circulator in an OR must be an RN.