Physician Assistant vs Physician Associate
The simple explanation is that the Physician Assistant profession and the Physician Associate profession are one and the same. The only difference is semantic. Yale University chooses to refer to this particular course of study as leading to a career as a Physician Associate. In either case these providers are certified PA's or in official shorthand, PA-C. The following explanation regarding their choice is from the Yale's discussion of their program as it appears on their website.
"The Physician Associate"
At the time of the program's inception in the early 1970s, the name of the PA profession and the associated training programs varied greatly. The term PA is now widely used to denote physician assistant; however, the program pioneers wanted to convey the collegial relationship that exists between PAs and their supervising physicians and thus adopted the term "Physician Associate." Currently both physician assistants and physician associates operate under the title of PA.