THE BIG difference is that you can actually get the 2004 edition. You have to give up your first born to get the new one delivered to you!!!!
Just kidding: Its just a guess, but I wouldn't think there is much difference in 2004 vs 2005. There weren't any new resorts, and the My way ticket info, and new dining plans, aren't even going to be included in the 2005 books, since they were to print before that info was released.
You can get any updates on their website to add to your current book.
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