Resident Evil 4 was originally developed and first released exclusively for the Nintendo GameCube.
The North American version was the first to be released and included all the game's original content and uncensored scenes of violence. When released in Japan, the game was censored by removing the decapitation scene when Leon is attacked with the chainsaw. The German version had the most drastic of changes applied to it, with much of the game's content being censored and/or cut.
This version has a number of special features and changes were made to the game. This version's graphics were made slightly inferior compared to the GameCube due to the PS2's hardware and many of the cutscenes were pre-rendered instead of being in real-time. The PS2 also introduced proper widescreen support unlike the GameCube version which was letter-boxed. The game was released on a single disc as opposed to the two discs that the GameCube required. Extras added included: a new side story with Ada called Separate Ways, a new set of special costumes, a new weapon, and a movie browser.
The Windows version supports play through a keyboard or gamepad. This version was criticized for it's poor graphics and lack of mouse support. This version contains all the extras that have been previously added on the PS2 version and also supports a variety of widescreen resolutions.
A port of the game was released on the Wii, under the title Resident Evil 4: Wii Edition. This version includes all the bonus content from the PlayStation 2 version, as well as a new control scheme using the Wii Remote and Nunchuk. It's also compatible with the Classic Controller and GameCube Controller, for those who prefer more traditional control schemes.
PlayStation 3 and Xbox 360
Another port of the game was released for the PlayStation 3 and Xbox 360, under the title Resident Evil 4 HD. This version of the game is identical as all the previous games with all the bonus content, the only difference is that it contains leaderboards and is displayed at 720p.