First of all, you must have the MSN, along with additional training, to become a Nurse Practitioner (NP, ARNP, etc...). You will take a separate exam to become a licensed as a NP.
Secondly, a Nurse Practitioner has far more formal education than your average PA...they are not similar at all. In fact, a NP may have an independant practice in many states, as well as prescriptive privileges, a PA does not and will never have that right. PA= Physicians ASSISTANT, ARNP= ADVANCED REGISTERED NURSE PRACTITIONER.