Similarities
With appearances alone, both consoles are virtually the same: same length, width, weight and color. They also play the exact same media and produce the same quality images at the same high-resolution (1,920 by 1,080).
Different Processors
The 60GB system has an IBM Cell 3.2 GHz processor, which runs faster and more efficiently than the Cell Broadband Engine processor of the 40GB version. As a result, the 60GB console has faster load times and saves.
Price Difference
The 60GB model no longer commands the $600 price tag it did on launch day, but retailers still have it priced at $430 in 2009. The smaller version can be found for between $300 and $330.
Connections
In addition to having a smaller storage drive, the 40GB model also has four fewer USB connections than the 60GB. This does not affect the number of controllers that can connect to the system wirelessly; only the number of external connections for USB drives or charging controllers that can be connected at once.
Backward Compatibility
The biggest difference between the two systems is the backward capability of the 60GB system, meaning it can support PlayStation 2 games. The 40GB system can only operate PS3 games.