It seems it has the same camera as the inspire (in a different package), the same flight controller, the same app, and the same Lightbridge HD downlink. The difference is the craft itself (the Inspire is faster, bigger, with retracts), the gimbal (the Inspire has a second operator option with yaw control), and the radio (the Inspire has HDMI on the radio while the P3 just has the USB out to a phone/tablet).
Just on first impressions I would say the P3 is the winner for the price for anyone who doesn't need a separate camera operator, ground monitor (in addition to a tablet for the flight app), or the increased speed/power of the Inspire. Those who need the added functionality the Inspire offers are, of course, better off with it.
Finally, the Inspire does have that detachable camera/gimbal feature. As of now it's pointless because there is only one camera/gimbal option available. In theory DJI could offer up others. A night vision option would be extremely cool. A nicer sensor/lens setup would be great too. But until DJI actually comes through with additional options this is irrelevant.