On the one hand there is the stable rom. This is the official and recommended rom version by the manufacturer. The stable version comes out every 2-3 months and does not offer root privileges.
Then there is the Developer Editon (= German developer version). This is actually, as the name already says, intended for developers. It does not differ much from the stable, but you get weekly updates. This version is just as stable as the other one, but offers the possibility of root privileges (by unlocking the bootloader).
Last but not least, there are roms from Xiaomi.eu: These are unofficial Miui roms with several languages (including German) and without China apps.