I honestly wonder if they're any different. On a PUP car, the door might also pop only slightly ajar, if you're opening it from the natural position, which is right in front of the falcon wing door sensor. The test would be to pop the driver's door from INSIDE the non-PUP car, and see how far it opens. This is the case where the PUP door will almost always open the distance given by the FWD sensor.
On the other question, I think the car stores some of the distance measurements from the sensors into memory. If I pull into my garage next to my S, and my daughter opens her FWD before I open the driver's door, my door still opens the correct amount. Just a guess, but it would make sense that once the car is put in park, it would save the state of all sensors and use those for decision making with regard to doors and wings and such. (And hatches, please?)