The comparison is not valid, as the games were not engineered for a specific target (1080p @ 60 fps, let's say). The beauty of consoles is that you don't have to create a plethora of settings and you get a single, non moving, target to get your program to run at.
Also, you're assuming the APIs will be equal in performance, which they won't. It is suspected the PS4's API will be slightly slower or more cumbersome than the native DX API the Xbox One is using.
Realistically, developers are going to develop a cross platform game that hits the target on the slower platform, cap the framerate at 60FPS, and release it for both consoles as is. We won't see any real difference unless the developers have some colossal failures like they did this gen (MVC3 framerate on the PS3 for instance... thanks Capcom).
We might end up seeing differences in exclusive titles, but those are hard to compare unless it is drastically different. A game having slightly more draw distance on the PS4 isn't relevant to compare against a completely different game on the Xbox One.
Some people keep saying this, but I'll believe it when I see it.
The performance gap between PS4 and XB1 is fairly massive. If it doesn't show in some fashion in cross-platform titles (less slowdown, more AA, whatever would result from the laziest devs possible), I'll be surprised.
One must realize that framerate caps aren't guarantees of constant framerate, just a limit that stops it from going above that limit. Many
many titles on 360/PS3 dip well below their target framerates depending on what's happening. Beyond that, many titles that aim to provide a truly consistent framerate have to be rendered below 720p and upscaled in order for that to be achievable. What we could see in some cases is native 720p or 1080p on one system, and an upscaled source on the other.
The API issue will be something to check into. After all, we have nothing concrete to go on right now. It could be that the OS overhead on XB1 negates any potential API advantages entirely, or worse.
I don't want to say anything silly, because we'll have actual games out soon. If they look absolutely identical, then I'm wrong. If there are real differences to be seen, then it will seem silly given the hardware gap to have expected them to be
truly identical.