At the risk of having my head (now peering over the parapet) shot off and without the benefit of my dusty PofF books to hand to confirm this I'm going out on a bit of a limb from memory....
Surely, the POR is the plane described 90 deg perpendicular to the AXIS of rotation (i.e. a vertical axis extending through the mast).
The TPP is the plane described by the rotor tips - nothing "Construct" about it TorqueTalk (lets discount the effects of tracking / out of track blades)
With cyclic input applied (and the effects of Hookes Joint, Flapping etc), the the TPP can describe a plane which is NOT parallel to the POR.
It is for this reason that the two descriptions (POR and TPP) exist otherwise they would be described by the same definition ... mange tout, non ?
... he ducks for cover awaiting a triade of "durr!" statements
FO