There is no difference between GOW2 and GOW2:GOTY except GOTY version has code hard paper for the extra maps.
If you want extra goody, you need to purchase new, not used from third parties.
I purchased mine from goHastings and they didn't send me the code which I believe it is only one time only used. I e-mail them but they said stupid things that they only follow what they describe in the describe section. They said 100% guaranteed and I'm not even closed to 100% satisfied.
It is partly my fault because I didn't research enough to buy this game. I should have searched more about this but I just figured that GOTY version included all the extra goods in the CD...not in separate code.
If you want just used game, buy GOW2 regular with $5 less price. There is a reason why third party don't leave full detail about this product because they are trying to trick you.
Microsoft supposed to make this GOTY version with better quality and better way, not just put one code paper inside of the package.
Thanks for posting this, I'm a new 360 owner and was looking to get this. That's too bad you for you, no idea why they would just give you a download code and call it a game of the year edition. I'll be sure to get it new, thanks.