When investigating advanced nursing degrees in order to begin work as a nurse practitioner (NP), prospective students will find both DNP and PhD programs.
In the most general terms, the DNP, or Doctor of Nursing Practice, is a clinical practice degree while the PhD, or Doctor of Philosophy, in nursing is a research-focused degree.
The scope of both the coursework and the ultimate applications of these programs can differ quite a bit, although both are terminal nursing degrees. That is to say that neither the DNP nor the PhD is considered "further" education than the other. Both DNP and PhD graduates can work as nurse practitioners once they earn the proper credentials.
That said, many DNP programs incorporate an NP specialization, while PhD-prepared nurses must typically pursue a post-graduate certificate to become an NP.
In terms of completing each degree, the requirements can differ greatly. In order to obtain a DNP, students must complete a clinical project that demonstrates intimate knowledge of evidenced-based practices.
PhD programs, however, most often have a focus on original research and research methodology, which results in a final research project and defense of a dissertation.