What makes a nurse "a nurse"? What distinguishes nursing from other health care providers? For those who are about to type that we "care", I...

A good starting point for thinking about this is to understand what defines a "profession". Bledstein's The Culture of Professionalism is a solid introduction to the concept (see reference 1 below)..

The first hallmark of a profession is a licensing or credentialing system. In other words, a mother who might be an expert at caring for a chronically ill child may do many of the same things as a nurse, but lacking a license or...

A good starting point for thinking about this is to understand what defines a "profession". Bledstein's The Culture of Professionalism is a solid introduction to the concept (see reference 1 below)..

The first hallmark of a profession is a licensing or credentialing system. In other words, a mother who might be an expert at caring for a chronically ill child may do many of the same things as a nurse, but lacking a license or professional credential, cannot properly be defined as one.

Next, a to become a nurse, one must have undergone professional training in an accredited school. If one does not have a degree in nursing, one is not a nurse. 

Although nurse practitioners have advanced degrees and do many of the same tasks as physicians, the main difference is that all nurses are focused more directly on the patient as a whole while doctors normally are more focused on specific diseases or problems a patient is having. 

While the roles of nurses and doctors are constantly changing, a general claim one could make is that nurses focus more on patient care and doctors on caring for diseases or other medical problems.