you are right some differences between 40GB, 80GB, rumor 120GB,160GB
What is the difference between the ps3 40gb from the 80gb?
The 40 gb cannot and will not play PS2 games because it's missing the emotion engine (CPU) and the GPU.
The 80 gb can play most PS2 games via software emulation. It doesn't have the emotion engine, but it does have the PS2's graphic engine.
The 80 gb has 4 USB ports while the 40 gb only has 2 USB ports.
The 80 gb has 3 flash drives (SD, CompactFlash
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Apparently, the 80GB version of the console is dead, and is due to be replaced by a 120GB or 160GB model bundled with the Dual Shock 3 controller