I've tested both, and the EdP's topnotes are more subtle. In the heart notes, the EdT has more and sharper floral notes, while the EdP softens the floral notes with woods and oakmoss. And finally, the base notes of the EdP have a richer chocolate/wood note as compared to the EdT.
I find EdP synthetic and cloying as compared to the EdT. Other than these, I would say they are pretty much the same to me. Since EdT lasts forever on me, I guess longevity difference would be pointless even if EdP lasts longer.