seble was pretty clear about this while he was writing the code for the engine redesign.
LP affects scoring in the paint, PE affects scoring outside the paint.
He said several times not to read any more into it than that. The engine doesn't distinguish between layups, dunks, jump-hooks, back-to-the-basket shots, etc. It's all either inside the paint or outside the paint.
I believe he did say that mid-range shots utilized some combination of LP and PE.
And of course don't forget that other rating affect scoring ability besides LP and PE (ATH, SPD, BH at least).