According to Engadget, the Xbox 360 Slim includes built-in Wi-Fi functionality. Earlier revisions of the Xbox 360 do not include built-in Wi-Fi connectivity, but an external Wi-Fi adapter is available for purchase separately.
The Xbox 360 Slim is available in several models. Although all versions of the Xbox 360 Slim include built-in Wi-Fi connectivity, there are notable differences between each model. The Xbox 360 S 4GB includes 4GB of flash storage rather than the 250GB hard drive found on the standard version of the Slim. A limited edition model was released alongside the game "Gears of War 3." This edition offers a "Gears of War" paint scheme and a larger 320GB hard drive, which is also available for purchase separately. The Xbox 360 E features the same built-in Wi-Fi connectivity found in the Slim but removes one USB port and the optical audio connections available on earlier models.
All Xbox 360 Slim models feature a smaller design than earlier Xbox 360 models. This design results in a lighter console that uses less power and runs more quietly than earlier models. However, the Xbox 360 Slim generates more heat while playing games than the larger, earlier versions of the Xbox 360.