Wow, that's an enlightenment for me. I kind of know what low post was, but i always thought that LI was for your bigs that have higher IS. Its hard to tell the difference between LP and LI, except for the fact, i guess about the pace of each tactic.
I always thought that LP was a bit further away from the basket, because LI, your passer looks for the player with the highest IS close to the basket.