Well, in terms of brute hardware and what's "under the hood", the XBox 360 overpowers the PS3 in nearly every category. First of the CPU, which the main core of how everything works. Both of the systems will have a CPU which runs at a speed of 3.2 GHz, but the 360's will/does have multi-threading capabilities meaning it can multi-task much quicker than the PS3. The GPU, which is the Graphics Processor, is a bit more of a tight race. The XBox 360's GPU will have more overall power, and the ability to generate more stunning, detailed graphics, while the PS3 will have a GPU which runs at 550 MHz, as compared to the 360's which will run at 500 MHz. (Speed)
And lastly, System Bandwith. The 360 absolutely kills the PS3 in this category, exceeding it by five times.
XBox 360 System Bandwith : 278.4 GB/s
PS3 System Bandwith : 48 GB/s
Source for info :
http://media.xbox360.ign.com/articles/617/617951/img_2812505.html