According to anonymous game developers, the PlayStation 4's superior hardware will give it an obvious and unassailable advantage in performance. The report states that memory reads on the PlayStation 4 are around 40 to 50% faster, and its Arithmetic Logic Unit is around 50% faster too.
What this translates to in real-world gaming, using a platform agnostic title as an example, is that if the game could run at 30fps at 1080p on the PlayStation 4, it will only do around "20-something" fps at 1600 x 900 on the Xbox One.
In response, this is what a Microsoft spokesperson has to say:
“Ten years ago, you could argue that a console’s power was summed up in terms of a few of its specs, but Xbox One is designed as a powerful machine to deliver the best blockbuster games today and for the next decade.
Xbox One architecture is much more complex than what any single figure can convey. It was designed with balanced performance in mind, and we think the games we continue to show running on near-final hardware demonstrate that performance. In the end, we’ll let the consoles and their games speak for themselves.”
To combat their obvious hardware handicap, there are also rumors to suggest that Microsoft would put pressure on game developers to ensure that the PlayStation 4 versions do not look much prettier.
These are still early days yet, and Microsoft could still yet make changes to their hardware (like the recent clock speed increase), though this is unlikely that it would be anything major at this point of time. In addition, game developers are only just working on the new consoles and will need time to figure out how to get the best of them.