The steelbook itself is different. Get two and hold them side by side. Huge difference. The Japan one has a metallic bling effect while the U.S version does not. The Japan version also doesn't have the writing "Anniversary Limited Edition on the top of the steelbook.
They are completely different.
The spine is also way different.
I couldn't get the bling effect to show up on the Japan one. It is a much higher quality print. The bare metal is brushed where as the U.S. version is plain. The moon on the Japan version has metallic while the U.S. version does not.
Japan steels are of different print runs. Its obvious when you have them side by side. Japan steel quality has been and will always be the best. I have had over 1000 Japan steels go through my hands in the last year. Its more than obvious the quality difference.