Jagji56: The GAME is identical. Hell, you can play The Witcher games without STEAM running, even if you got them from STEAM. you just have to go to the common folder, and boot the .exe directly.
Really? Back around Witcher 2's 2.1 patch, the launcher broke and the only way to start the game was to run the .exe to bypass it. Multiple Steam users reported that they weren't able to do that, though. I guess they must have made it truly DRM-free on Steam at some point after that.
Or does the Steam version load the launcher when you run it directly from the .exe? The GOG version loads directly into the game, so if that's the case, the two versions are definitely different on that point.