I don't think there's any real differences between the CE and the normal edition, however there are four executables on the disc.
DX9 with a X86 (32-Bit) and X64 (64-bit) executable, same with the DX10 EXE.
That's probably why the game doesn't work on X64 systems as the game detects such things and installs the appropriate exe files. (Either the two X86 exe files for both DX10 and DX9 or the two X64 exe files again for DX10 and DX9 - multiplayer also uses it's own executables but it's online so there's no need to do trainers for those files. )
EDIT: Based on the above replies it seems there might be some differences after all, interesting. (Wich would be a problem as the CE is limited to 20K copies and nearly all of those are sold out.)
where does it show what dx you have i bought a norm version
If you are using Windows XP or Media Center Edition 2005 you have DirectX 9 but if you are using any flavor of Vista you then have DirectX 10. Also you can check the game at the options screen and it will tell you either DX9 or DX10. Good luck and happy demon killing man....