What does upscale mean?

its when you make the pixel count being outputted match the number of pixels on the screen.  Despite the fact that the native resolution and the resolution of the screen are different.  They basically just multiply pixels to match the screens resolution, so there will be 2-3 pixels that are identical (thus giving no extra detail, but looking better).

In every system and for every problem, there are a different set of bottlenecks. These are the areas of the system that are slow relative to the rest of the system in attempting to generate a solution.

The PS3, for example, has very little fill rate. It has approximately a Geforce 7600, and if you know anything about video cards, that's extremely slow these days. The Xbox 360, on the other hand, has a fair bit more fill rate (still, very, very slow compared to modern computers) which allow you to either:

(1) Fill a higher resolution
and/or
(2) Add more texture passes (lighting effects, bump mapping, other effects).

This can explain differences in games like Fight Night Round 3.

Another common bottleneck is memory, but the differences between the PS3 and the 360 are very small here, and it's a complicated discussion.

The Cell and the Xbox 360's Xenon processor cores are *much, much* harder to compare, as they're almost entirely different. The Cell has 1+7 processing units. It has the core, and seven extra processing units that can assisted with floating point calculations. This means that these seven aren't full processing units in the sense that they can do anything, but rather that they can solve a specific type of problem. Specifically, they're good at calculating values that need high precision, the type of which are quite common in games. Sony calls them SPEs.

However, the Cell's bottleneck is often its central / general purpose processor. When it has problems that can be solved entirely with the SPEs easily, such as folding @ home, it can generate huge performance. And developers can rewrite parts of their game engine to rely primarily on the SPEs. Things like physics translate well. Other areas don't translate as well, but they can still be farmed off to the SPEs at a performance penalty. This doesn't matter, however, because you have so many SPEs that you don't mind the performance penalty. Some problems, such as Artificial Intelligence, are not suited to be run on the SPEs and require the central processor in the Cell.

The Xbox 360's processor, on the other hand, is much simpler. It's a 3-core solution, effectively offering about 3 times the performance of the Cell's central processor and none of the benefits of the SPEs.

Direct comparisons here are nearly impossible. The Cell is very clearly better for some things, and very clearly worse for others. On paper, the Cell's numbers were phenomenal for the time when it was released.

Any reasons why the Xbox 360 version of GTA has more resolution and the PS3 version seems to look better offered here are most likely speculation, although some of it can be informed speculation. Frankly, I don't think the game looks good on either system. They're both video game consoles, and both woefully slow compared to modern PCs.

Since I don't look to video game consoles for amazing graphics (for obvious reasons: they suck at them), I don't care if there are slight differences between games.

 I'm playing my games in 1080i on the xbox 360, is that upscaled?

Halo 3 is an excellent example of the latter.

Buffer or whatever your saying aside, the difference is small but its there. The ps3 is stonger accoording to every dev out there. And thats pretty much it. It can hold a lot more onscreen, bigger disk space, cell and seven processers (xbox only has 3 and tops DVD9 vs blu-ray up to 50 gigs so far.)

 ps3 has more high resolution games that do NOT upscale but are native 1080p. so i would guess that since xbox only has 3 native 1080p games and ps3 about 25 that ps3s frame rates are much better. Since it takes more power to run in 1080p native then 720p and then upscale.

man i'd already given up comparing graphical differences between the 2 consoles. COD4, GTA4 are simply too cool and fun. when i immerse myself in the gaming these differences r too tiny to distract me.
unless the graphics difference is too great and noticeable such as games like lost planet, then it is worth to be discussed. n no more blaming on either console's abilities since game after game proves that both consoles are capable of achieving the same performance. we can only blame lazy developers when they are doing the porting i suppose.

What do you mean "but"? I would have to state the difference was not there for it to be a "but". Since I stated there was a difference, you just "corrected" me with my very point. Try actually reading my posts properly before you reply.

As for the buffer part, that is what the two parts of the VRAM are referred to. The texture buffer is the actual graphics, and the frame buffer is making them visible. 

No, that's not true.  The PS3 doesn't have "seven processors", it has a PPU and seven SPUs.  In reality, for most game engines, the SPU/SPEs are not the bottleneck, the PPU is.  That's where the Xbox has an advantage.

But you can use the SPUs to make up for the lack of as much general processing power as the Xbox has, to a large extent, and they can even do some things faster. 

This part just isn't true.  You're wrong. 

The bottom line is this: while the PS3 and Xbox 360 are pathetically weak compared to even mid range modern computers, they're fairly evenly matched assuming a dev is willing to take time to rewrite parts of his engine to rely primarily on the SPEs.

Game engine and assets wise the game is 360 orientated with development lead on the 360. In this sense the game is far more representative of the 360 hardware capabilities, would the game have been a PS3 exclusive the game engine design (and also assets wise) would have been different.

Looking at the way the graphics are rendered (enlarged images to make differences in rendering more profound):

360:



PS3:



360:



PS3:



Why does the PS3 version look more realistic and cleaner?

It appears to be better lighting and Anisotropic Filtering (AF).