Maryland Academy does a good job explaining differences between PA and NP. Recent change for PA's - certification is now every 10 yrs. And another addition to the site's list, PAs can go into WHATEVER field they want to and can even change specialities whenever they want. NPs cannot.
Phipps Conservatory and Botanical Gardens, Pittsburgh, PA ~ LEED certifications: 1) world's only Platinum-certified greenhouse and 2) Platinum-certified and net-zero energy Center for Sustainable Landscapes.