Models
The 40GB PlayStation 3 is one production model released for both NTSC and PAL countries beginning in late 2007. North America and Japan receive NTSC consoles, while Europe and Australia receive PAL consoles. An 80GB PS3 was released in late 2007 for NTSC countries, and in late 2008, a different 80GB model was released for both NTSC and PAL countries. The two 80GB models have slightly different features.
Hard Drive
The most obvious difference between the two models is the hard drive size. The 80GB PlayStation 3 can hold twice as much data as the 40GB version. More casual gamers likely never will fill the 40GB hard drive, which gives no real advantage for having the larger hard drive. Serious gamers and people that download large amounts of content offline will need the extra storage space.
Backward Compatibility
Older PlayStation 3 consoles could play PlayStation 2 games. This feature was phased out by late 2007. The 40GB PS3 was the earliest PS3 model to remove the backward compatibility feature. The older 80GB PS3 is backward compatible. If an 80GB PS3 has four USB ports, it is an older model, which is backward compatible. The consoles also have serial numbers in the form "CECHExx."
Price Difference
The 40GB PlayStation 3 is cheaper than both 80GB versions. The older 80GB version is about $50 more. The newer 80GB version is only about $20 more. The older version is more expensive because it has more USB ports and backward compatibility. The 40GB and 80GB models no longer are being produced, so they mostly will be available as used consoles.
Which is better?
The older "CECHExx" 80GB PS3 is the best investment of the 40GB and 80GB PS3 models. It is the most expensive of the three models, but the backward compatibility and extra USB ports make up for the slight price increase. The newer 80GB PS3 is a close second. Doubling the size of the hard drive for a $20 price tag is more than worthwhile. A 2GB memory card for the PS3 costs more than that. The only advantage to the 40GB PS3 has the slightly lower price.