WIND-The heavier P4 can handle high wind better than the super light Mavic drone.
CAMERA-the P4 has a wider camera angle, sharper image and does not require tap to focus as it remains in focus automatically guaranteeing great video quality
BATTERY/FLIGHT TIME-It remains to be seen but I suspect the robust batter of the P4 will give you slightly longer flight times
DESIGN-the P4 is a better looking drone with smooth, strong, muscular lines and curves...grrrr

Here is wher MAVIC is better
PORTABILITY-The Mavic is small
RANGE-The P4 range absolutely SUCKS....P4 range is awful. God awful. Worse the previous versions. The P4 range is absolutely disgusting. The Mavic can fly much further distances. You can fly it behind walls, trees, buildings etc.

Myself and many others have had the P4 out 4-5km.
If you are having range issues and are flying in an interference free area, please contact support and send the aircraft in for evaluation.

WIND -- Not true.  See youtube videos including the leaf blower vid
Camera -- Wider yes.   Some people prefer the targeted focus rather than just fixed.  gives you more flexibility
Battery -- 27 mins on the Mavic.   Sounds the same to me
Design -- Negative Ghost Rider.   The Mavic is a bad ass Coupe and the P4 is now a big fat Oldsmobile

MAVIC DOES BETTER IN WIND.
MAVIC HAS = SIMILAR FLIGHT TIME
WIDER IS NOT BETTER.  JUST DIFFERENT.

Here's a great review.