Ok, so this is not another GTA4 thread, but I am going to use that game as an example. It's purely a hardware discussion.

On the 360, GTA4 has 80 lines of resolution more then the PS3. All things equal, more resolution = better visuals.

But the 360 version actually looks worse. Why is that? For that to be the case, the PS3 has to be better in other areas to compensate for the loss of resolution. What are those area's? Are they lighting, pixel shading, AA, frame buffer? I hear the 360 has a more powerful GPU, so where is the issue coming from? I know pop up is from disk speed, but I am not talking about pop up.

Does anyone have a white-paper then can direct me to on this, or a clear explanation? 

My guess is that the speed of the Cell allows for better bandwidth use of the texture memory (since the other aspects of RAM, like size and speed, are fixed). This may not be the case with the frame buffer, which had to be reduced to make room.

So the things that are slightly better are part of the texture memory, while resolution is part of the frame buffer, which is not part of the memory of the 360, and thus slightly higher on that system.

In other words, it supports my claim that the 360 actually has a better frame buffer, but that the PS3's texture memory may be better utilized.

Well I won't pretend to be an expert on either console hardware but rendering at higher resolution takes more hardware power. Its the reason games like COD4 and Halo 3 run at a lower than HD resolution. Lowering the resolution allows for there to be more processing power to be dedicated to additional effects.

The most logical response (from what i have heard) is the use of a nice upscale technique (this is why the PS3 version looks more smooth)... like GT4 (they are using horizontal upscale)...

And again, maybe the trend on power terms is for the PS3, but since GTA was build with the 360 in mind, maybe the engine couldn´t be adapted to use more of the PS3 teorical power...

The difference has nothing to do with hardware, it has all to do with programing on this game.

To use the graphical power of the PS3 you have to use the spus to do some of the work on the graphical side. A lot of game designers still havent figured out how to use the spus correctly (usually when they port the game) so multiplatform games often look better on 360.

@ FJ-Warez and @xenophon13. The PS3 is the one acknowledged to look better. It's the resolution that's the issue and the SPEs don't look as though they can get around that, so texturing is focused on.

 Of course, and as I said, the best looking image (talking about the smooth only) is for the upscale according to the guys on beyond 3d...

Then the engine was adapted, just using the smaller frame buffer to accomplish it.

There is very little difference between the PS3 and 360 when you put the same game side by side. Both consoles look great in HD. The PS3 has the advantage due to its hardware being more reliable.