I own and like both. I bought the Pure Parfum first (coincidentally, there is no EDP version of it, just EDT and Pure Parfum) and later bought the EDT. They are very similar, but there are some very minute nuances. The EDT is slightly brighter and more citrusy, with a bit more citrusy punch, if you will. The PP is softer, slightly more woody. They are like twin brothers - you may not be able to tell which is which if you see them separately, but if they are next to each other, you may be able to pick up on the slight differences between them.
I used to wear the EDP, originally, as I liked the more woody drydown, and that's what I originally bought. However, one day I bought the Terre d'Hermes aftershave balm - and I had an epiphany. The aftershave balm has MUCH stronger citrusy/zesty punch, extremely invigorating and refreshing after a nice shave. But of course this being an aftershave, this was a fleeting sensation that lasted mere 30 minutes or so. So I thought I'd revisit the EDT, bought a bottle, and sure enough - the EDT is a little closer to that clean burst of citrus and orange (the aftershave is still stronger though). I really enjoy the EDT now, more so than when I originally tried it, and I think I wear the EDT a little more frequently than the PP these days. This may change a bit in the winter, I think I may switch more to PP, and keep the EDT for warmer days.
Either way - they are both fantastic, you can't go wrong with either one. They are both versatile and smell great, and regardless of what some people keep saying - the EDT lasts just about as long as the PP (a good 8+ hours). Whichever one you pick, if not both like I did, I would only highly recommend getting the aftershave balm as well. If there was a way to make it last a few hours this would be my preferred scent of these three, as it has a very nice and crisp citrus/orange/pepper kick that I wish would last a few hours.