Normally third party dev won't drop frame rates, between the system what they normally due is drop the native resolution so if they have a game that will say run on the PS4 1080@60 fps then on the Xbox it will run at 900p@60 fps and the xbox will upscale it to 1080p (similar how 4K TV upscale 1080p signal). There are games that only run at 900p on PS4 then it up scales to 1080p, so the Xbox would probably run at 720p and again upscale to 1080p.
So yes the PS4 is graphically stronger than the Xbox mostly through the use of GDDR5 memory, however I will say this "most" professional reviewers (i.e not some fanboy on a forum) would be hard pressed to tell the different in most games if they were being played side by side even with the...