What you said is basically true. If I recall correctly, the PS3 GPU has a slightly higher clock frequency than the X360 GPU (i thought 750MHz vs 700MHz). Since the Xenon on the X360 has the unified shader architecture, every lane can handle every single graphical calculation. It can actually also be programmed to calculate physics or specific tasks, but was mainly build for graphical calculation (of course..) So you basically give it work, and it does it. The PS3 GPU however can only calculate specific tasks in specific lanes, which means, almost always some of the lanes have nothing to do, while others are being overthrown. This is the drawback of the PS3 GPU, but it can be helped with the SPE's of the cell. But since this is about the GPUs themselves and not the whole system, on average I think the PS3 GPU has an average efficiency of about 50-60% (if you program a game really well it might reach 70%) while the X360 GPU has about 90+% efficiency at all times. Besides this, the memory also plays a role. The X360 GPU shares its memory with basically the whole system. So if the GPU needs 350MB for example, they can program it that way. For the PS3 however, it's stuck with 256MB because of the split memory, and this limits the GPU. So yes, the GPU on the X360 is superior to the PS3 GPU in every single way.
Truth does not fear investigation
