What the difference between the Honda Element EX and the EX-P ?

Just different trim levels.

agreed.

It's my understanding that EX used to mean the trim which had black panels on the outside along with the car color, and that EX-P meant that the black panels were painted, too -- so the car was all one color. Around the 2007 model year, this changed and they stopped saying EX-P and went back to using EX for all the models at this trim level. As far as I know, the P just meant "painted," which used to cost $500 extra.

there both the same but the ex-p means that the plastic panels are painted. but the ex there not painted

The black plastic panels are painted to match the rest of the car.