First thing, I knew right away that the “P” could not stand for pigtail because the more-common 34 and 7002 models have pigtail connectors, and they don’t have “P” in their model numbers. If P stood for pigtails, then the model numbers would’ve been 7002P and 34P; but that was not the case. Second, I remember reading someone’s comment (either on Facebook, Reddit, or YouTube) that the “P” meant higher input power. But then in this link below, I found out that “P” means polarized.
Interestingly enough, Wheelock also manufactured the 32PT and 32PT-WS models. But I’m not sure if 32P/32PT was still made after the grille redesign.