After medical school, residency begins. They have no power. Nurse Practitioner - Nurse practitioners are nurses with an advanced level of knowledge and education in both nursing care and human physiology. They practice in a variety of settings and may provide primary care to defined subgroups of people. This includes advanced management of disease states and pharmacology.
Some states permit prescription writing.
Credentialling varies from practice area and state to state but in general, most have at a minimum a bachelor s degree plus some post-baccalaureate schooling. Many have master's degrees and some doctorates. A rank, not a job title. A major difference between RN an LPN training is that in RN programs more time is spent on theory and rational. In LPN programs the concentration is on learning specific skills.