In the Panda3D/python directory there are two python executables- ppython and python. Which one should I use, and what is the difference?
There is no difference. python.exe was just copied and renamed to ppython.exe. The reason why it’s convenient to use ppython is that no other Python distribution uses that name, so when you type “ppython” you are guaranteed to get Panda’s Python instead of whatever other copy you might have on your system.