Every time you begin a replay game, a number of things will be added and/or changed.
The Xbox version contains a lip sync bug. Since the PC version is a direct port of the Xbox version, the lip sync bug is also present.
This one will only make sense for those familiar enough with the game:
The Director's cut has been released for PS2 early in 2003. It featured the same bonus chapter that the XBOX version had.
This one just may have past unnoticed by most people playing the game: once you get to the Lake View Hotel, if you try to read the letter from Mary you will find out the paper is totally blank! Spooky...
Remember the mannequin in the Woodside Apt Buildings, the one that was holding the flashlight? In case you didn't notice it, the clothes on the mannequin are the exact same Mary is wearing every time James has a flashback about her!
Silent Hill 2 —and the previews of SH3— reveals the "SH series" as a multi-character based series, in which the different chapters will solely have in common the physical location the action takes place in —this is, Silent Hill.
In X-Box version of the game, in the new sub-scenario called "Born From A Wish" you don't play as James anymore, but as Maria thus giving you a different perspective on the game, and patching some questions that were left unanswered when playing as James the original "Letter From Heaven" scenario.
In the original Silent Hill, the fog was used to cover up the draw distance, due to the limited memory of the PlayStation.
In the XBox version of Silent Hill 2, the extra scenario, Born From A Wish, contains an extra four to six hours of gameplay, on top of the standard game.