This should become interesting
I have the german releases
Alien - 2-Disc Special Edition (Disc 1 containing both, the 2003 Director's Cut and original 1979 theatrical edition, Disc 2 the typical extras as Making of, documentary, production still collections etc.) - released in 2004 (originally contained a free ticket for Alien vs Predator and a preview DVD for AvP as well)
Aliens - 2-Disc Special Edition (Disc 1 containing both, Cameron's 1991 extended edition and the original 1986 theatrical edition, Disc 2 Making of, documentary, Production stills etc.) - released in 2004 (containing the same AvP stuff as the Alien Special Edition DVD)
Alien³ - 2-Disc Special Edition (Disc 1 containing both, the original 1992 theatrical edition and the 2003 extended edition, Disc 2 Making of, documentary etc.) - released in 2004 (also the AvP preview stuff is contained)
Alien: Resurrection - 2-Disc Special Edition (Disc 1 containing both, the original 1997 theatrical edition and the 2003 extended edition, Disc 2 Making of, documentary, interviews etc.) - released in 2004 (and even here containing the AvP preview stuff)
Those should be nearly identical to their UK counterpart releases (even the covers are similar)
The only difference are german subtitles and german audio tracks added (german subtitles only for the bonus discs)
Prometheus - standard edition (single disc release), the only bonus material on it are deleted and alternate scenes
Should be identical to all other european releases (except that for the german speaking countries it contains the german audio track, logically, and even subtitles in several languages like german, dutch, french, turkish etc.)
Predator - standard edition (2010 single disc reprint), it's the same Disc 1 as in the original 2001 2-Disc special edition release (even the code on the disc is the same) ... only exception: it was the very first time it was released uncut in germany! But there was already an uncut version for the german market back in 2001 (this disc is based on that one) released in austria and switzerland only, since in germany the uncut version was banned until 2010 ... It also got a new cover and disc image ...
Predator 2 - standard edition (2001 single disc release), this is the german uncut release only to be released in austria and switzerland (sadly the uncut edition is still banned in germany), it's the same disc as Disc 1 of the 2001 2-Disc special edition (only released in austria and switzerland) - there was also a 2010 release in germany, it was the very first time it was released in germany at all - but: cut (approx. 10 minutes missing), so I went over to catch a friend of mine in austria to get the uncut release for me
Ironically, back in 1997, when I saw both Predator and Predator 2 on TV the very first time, both films were actually shown uncut!
So I assume, the ban of the uncut editions of both films occurred later ...
Predators - 2010 1-Disc standard edition (released at the same time as the 2010 uncut release of the original Predator and the heavily cutted down edition of Predator 2 mentioned above)
It's identical to the italian release (contains both, german and italian audio tracks and subtitles), but the cover is different ...
Alien vs Predator + Aliens vs Predator: Requiem - 2-Disc double feature edition (released in 2008), it was a 2in1 budget repack, containing exactly the same disc 1 from the Alien vs Predator 2-Disc special edition release of 2005 (even the disc image is the same with the facehugger motive) and the same disc of the FSK18 (that means 18-rated) regular uncut (there was also a FSK16 - 16-rated - cut version) 1-Disc release of Aliens vs Predator: Requiem (released shortly before, it also has the same disc image of that release) - Well, it was much easier to track down that one than the uncut single disc release of AvPR, so I got this ... and I also had no copy of the first AvP at all, so it was just a logical (and time and money saving) alternative
As for the extreme/extended editions of AvP and AvPR: They never got any release in germany at all (but at least in austria and switzerland as fas as I know), but that's at least no problem to me, since I always prefered the original theatrical cuts more ...