Both nurse practitioners and physician assistants can be found everywhere in healthcare-related facilities--in medical clinics, doctor's offices, hospitals, and even in operating rooms. Oftentimes, they're performing duties you might be more accustomed to seeing handled by a doctor, such as conducting physical examinations, diagnosing illness, and prescribing drugs. While there are some differences between the nurse practitioner and physician assistant, there are not as many as there used to be.