@quaiky
Very nice text, however you missed the eDram on X360 and 1080p picture takes about 1920×1080*24 bits=~6MB(Of course it depends how many colors you will use, but its usually true color all the way today.). PS3 SPUs also have small amount of memory as well(256kb each, like Plaupius stated).
eDram on X360 acts like larger cache. Its only 10MB, but its also 10 times faster than regular ram so stuff you need more frequently with CPU or GPU go there while they are processing it.
@Plaupius
Higher resolutions call for higher triangle count models, and as Deneidez explained, each triangle needs 3*3*4 bytes of memory, and triangles are what constitute the geometry of the scene. Crysis, according to the tech demo, can have about 2 million triangles in one scene, so that's about 70MB worth of geometry data.
Well, as I also said they usually use triangle strips & fans to minimize amount of geometry data. Depending on complexity of meshes they can save a lot of memory. Lets take a fan for example:
You only have to store ABCDEF thats 3*6*4=72 bytes. If you use only triangles you would have to store EFA, EAD,DAC,ACB and that means 3*4*6*4= 288 bytes which is four times more than with fan.(Of course you have to store the indication, which one is it. Fan or strip, but it doesn't take 4 times more bytes.) :)
@el_rika
It's actually quite the opposite (PS3 version has the more detailed textures and mapping compared to Xbox360 version, while suffering from framerate and AA issues), but you just choose the wrong example, i understand what you're saying.
Actually its tradeoff for some other effects like shadows.
http://www3.telus.net/public/dhwag/FO3360.jpg
http://www3.telus.net/public/dhwag/FO3PS3.jpg
As you can see shadows are blockier on PS3 than on 360. The blockiness comes from technic called shadow maps for dynamic shadows. They are like large textures which indicate where shadows are. So less you have memory for shadow maps blockier they are.(Yeah, you can postprocess it, but with small shadowmaps its quite hard.)
So basically the more complex the game engine, the more suited the PS3 is for development.
Actually its quite opposite. More complex it is harder it is to make work on PS3. On the other hand simpler it is larger the gap between PS3 and X360 versions can be. Thats why for example GT5P works nicely on PS3(and might be impossible to do on X360). Its very simple compared to most of games out there. However both machines cant beat even older PC when it comes to more advanced stuff like logical AI for example. (Strange thing is that original Xbox could do the same as PC.)
Essay Pro
