Typically, your result is going to be better with a physician. Dermatologists usually do their own.

While it is difficult to say what the skill of that particular nurse is, it is my feeling that  most dermatologists do their own injections (as is the case in my office).  Because I do my own, I feel that my patients are getting the absolute best that I have to offer.  Also, if a nurse is doing it, there is always the chance that they haven't worked for that practice all that long and might not be all that good.

In general, plastic surgeons tend to delegate these procedures to other people in order to generate more revenue, while dermatologists tend to take more of a role in doing their own procedures, believing that it is important to do it themselves and offer the best 'injector' to the patient.  Hope that helps!