Ok this is my personal opinion so it may be wrong/ disagreeable but here goes...
I think that a Doctors role is largely based on decision making while nurses simply orchestrate what the Doctor has told them to do, such as take bloods or blood pressure. You could mention work experience, and how there is a distinguishable difference between the Doctor and Nurse. Nurses are obviously vital to the team dynamic, but I think the Doctor has more control over what happens tot he patient, and it is this responsibility and challenge that appeals to me.
*yeahh reading that back, I wouldn't give me an offer lol