Instructions
Determine the model of the 80 GB PS3 you're comparing. Three 80 GB SKUs are available. They are CECHE01 and CECHK01 or CECHL01 (the latter pair have the same features). The model of your system is located on the rear of the console or on its box.
Determine the look you'd want for your console. All 80 GB PS3 consoles are black with chrome or black with silver trim. The 20 GB model is black with black.
Consider the power consumption of each console. While this doesn't make much of a difference, newer models consume less power. The 20 GB model and the CECHE01 80 GB model are 180W. Both the CECHK01 or CECHL01 80 GB models are 110W, 70W less than the earlier models.
Consider the number of USB ports you need. The 20 GB model and the CECHE01 80 GB model each has four USB ports. The newer CECHK01 or CECHL01 80 GB models have two apiece. Also, the CECHE01 80 GB model is the only unit with a built-in flash card reader.
Determine whether you will be connecting your console. If you want to connect to the Internet using your PS3, all three 80 GB models have built-in Wi-Fi. Unfortunately, the 20 GB model lacks this feature, meaning you need to physically connect it to your modem.
Consider the controller you need. The SIXAXIS controller included with the older models lacks vibration, while the DualShock 3 controller includes it. The included controller is listed on the console's box. All controllers are recharged by connecting to the console's USB ports.
Determine whether you need PlayStation 2 backward compatibility. While all PlayStation 3 SKUs can play PSOne games, only select consoles that can play PS2 titles. The 20 GB model is almost 100 percent backward compatible with PS2 titles, with the hardware to play the games built into the console. The CECHE01 80 GB is backward compatible as well, but by using emulation; this means it's not quite as capable as the 20 GB model, but can still play older titles. Both the CECHK01 or CECHL01 80 GB models are completely stripped of PS2 backward compatibility.
Compare prices. Odds are you'll have to buy the 20 GB or 80 GB PS3 used, as both are out of production. Search on eBay, Amazon, or Craigslist for prices. Local pawn shops might also have the console for sale. Because both systems are out of production, the price is set according to the seller, so shopping around is your best bet to save money.