So what exactly is the RAW figure in terms of power difference between X1 and PS4? I hear 40%... I hear 50%, which one is it? If a developer puts in the same effort for both platforms would it be 1080p vs 720p all the time or 1080p vs some odd number say, 812p?

What was the power difference between the original XBox and PS2?

Depends on how intensive the game is GPU wise. But common types of games like fps and tps, 50% is easily the gap if the eye candy is jacked.

Is this confirmed?

According to the  math it goes by the maximum amount of operations per second.  In this case its Trillions. 

Xbox One 1.31 Trillion operations a second in absolute perfect conditions.

PS4: 1.84 Trillion operations a second in absolute perfect conditions.

1.84/1.31 = ~40% raw power advantage of the PS4..

These numbers refer to the hypothetical limit of each systems GPU. It represents the  maximun output performace in terms of graphics and GPU computing. 

It was 50% at start but before launch MS upclocked 57Mhz in GPU... so that make the GPU jump from 1.2 TFLOPS to 1.31 TFLOPS.

It is hard to tell about Xbox and PS2 because they had way too different architectures... Xbox was stronger but how much? Well it was a good gap but it is discussable... in my opinion the gap was small or close to that showed between PS4/Xbone but some guys will disagree and says it was a bit widen.

The PS4 and Xbone are easy to compare because they use 90% the same architecture... the only differences are the GDDR5, DDR3 + ESRAM, RAW POWER and clock of the components... everything else you can say they are brothers.

Thanks for the answers it's appreciated.

By my laymen judgement the difference is larger than 15-20% - the numbers look far more impressive on the PS4 side of things

Whether the gap in performance grows smaller or larger - we'll see. At this point it is pretty small. Noticable, but really small. I can see it grow larger as time goes by and devs take advantage of these extra numbers the PS4 offers, I can see it stay at current level, but I can't see it ever grow smaller, unless devs deliberately choose to ignore the extra horsepower.

Though I have to say that my mind will be totally blown away if the gap grows into 1080p@60fps vs 720p@30fps. That sounds unbelievable to me, especially the 60fps vs. 30 fps part.

Whether true or not, we should be expecting more of this sooner rather than later. The games are becoming more demanding on PC with requirements like 4-6gb VRAM under the settings. Even some PC gamers may have to change some things in their rigs to play some of the games coming at a sustainable framerate. What am worried about is that in less than a year the xbox one is still having problems atttaining 1080p in most of their games. The rest that are 1080 are either done for parity (because the PC version ends up the best as always) or an advanced grpahic setting ends up missing. This isnt a very good sign for games coming in the years ahead.

That's an opinion easy to have if you aren't very familiar with the OG Xbox. It genuinely felt a generation ahead when you played games like Doom 3, Riddick, Halo 2, Half Life 2, Fable, etc. Ports of PC games from Ubisoft also looked much better on Xbox.

With X1 and PS4, the biggest disparity seems to be performance.

PS2 was technically inferior and simply can't replicate the visuals we saw on Xbox.

But PC games have always had higher spec requirements.

When the 360 was released I don't think I was running less than a 1GB of RAM. So the Xbox 360's 512MB didn't seem like much. The OG Xbox did amazing things with a measly 64MB of RAM.