Music wise there's a lot out there. It appears that the special vinyls are out of stock, but here's what I know of thus far:
Blue vinyl
Black vinyl
Clear vinyl
Euro/UK 3CD digipak
Euro/UK regular 2CD edition
US 3 CD digipak
US regular 2CD edition
Japanese 2CD/1DVD (LoudPark 13) limited edition
Japanese regular 2CD edition
Things to know. The Japanese limited and regular editions both come in old style fatboxes. Their booklets have the front cover that you see on the digipaks, so they have, technically, four more pages. Thus, the Japanese booklet has the thanks page for the Universal Choir.
It's not the FULL listing, but it does have its own page. The choir sheet is also in the Euro/UK/US regular edition books - because of the extra page count. In the inside front cover of the Japanese/Euro/UK/US booklets is also a dedication quote from Devin.
All the vinyls are the same in that they are all pressed and put together in Germany. The only difference is the color of vinyl. The LPs have the FULL choir sheet with every name that participated in the choir. The sheet is in the back pocket of Sky Blue. All the vinyls are 4 LPs and have printed inner bags that cover lyrics, credits, etc. The LPs are the only versions that have a stand-alone Dark Matters and stand-alone Sky Blue. Both LPs come together though in a solid color silver foil box with the embossed Z2 logo.
Now we get into the 3CD digipaks.
Both the Euro/UK and US versions are printed on silver foil stock and are digipak format in a slipbox. The slipbox is embossed with the Z2 logo. Now I have both versions and find the Euro/UK version better in quality. Why? The box is heavier and wider, as is the digipak itself. The stock just seems to be a heavier. Plus the entire digipak inside and out is in foil stock. The US version does not have foil stock on the inside. And in my opinion uses a thinner stock of paper. The Euro/UK also has the image straight through the digipak, from front to back. The inside of the US version has black between the sections of the digipak where it folds. Also, the US digipak has a slight purple tinge to the slipbox. I don't know if this is intentional or not because the US version is printed in the US and the Euro/UK in Germany. It could just be a printing thing. The US digipak is also slimmer. And in my case, it also seems that the slot where the booklet goes, in the US version, isn't made as well as the Euro/UK version, as it took me several buys and returns, until I got two copies where the slot was intact and not ripped on one side or the other. I had no such issues with the Euro/UK version. I forgot to mention that the booklets that are in the digipaks are cool as well. In both the Euro/UK version and in the US version, the booklet has the album covers as the front and back. So, if you're looking at Sky Blue, flip it over and you've got Dark Matters! However, they do lack the full "thank you" page for the Universal Choir participants, and the single page with Devin's dedication quote.
The Dark Matters discs themselves are also slightly different in color between all versions. The Ziltoid text on the CDs themselves is not as sliver and shiny on the US version as the Euro/UK version. The Euro/UK CDs are also darker. The Japanese Dark Matters disc is much lighter in color that either of the other versions. Other than that there is not much of a difference. I don't really see any difference in the Sky Blue discs.
I only have the US regular edition, so the discs pretty much follow the same pattern as stated above.
If you're into Ziltoid "stuff" there are (were) pre-order bundles that included a Frisbee, Dark Matters t-shirt, Z2 metal (of course metal) keychain, which has Z2 engraved on the back with the release date (pretty cool).
Overall, there is a lot to choose from. The packaging of the LPs and digipaks is some of the best I've seen. This ranks right up there with the last Hell album. That digipak is really fat, but it opens into a full Ouija board!
If I've missed anything feel free to add. But most of all enjoy what Devin has so awesomely presented us with. It's products like these that justify my reasons to buy tangible music.
Peace.
-T