Are there differences on the Japanese version? I'm in the navy stationed in Japan, and I saw both of them in a Japanese theater...they weren't any different from the US dvd releases.
If there's any difference between the Japanese and US dvd's, I wouldn't be downloading the Japanese version. Just order it online and play it in a region-free dvd player.
I've also heard that they're releasing a director's cut, which will be the entire film in one piece, instead of in two volumes. I'm not sure whether or not that's been confirmed though.