Ich habe ein Telefon. <- Standardized West German (SWG)
Ic habe eine Telafone. <- Standardized East German (SEG)
I ham an Telfon. <- Standardized Bavarian (SB)
With the split of Germany into 3, the USSR and USA both made differently standardized versions of the German Language.
The USA sponsored the Bavarian Language in their puppet-state of Bavaria, in order to make sure Germany would never be united again, and pose a threat to Europe.
The USSR made Slavic-originated words much more common, compare "Maschinaoruzen (Machine-Gun in SEG)" to "Maschinengewehr (Machine-Gun in SWG)", or "Kompenuter (Computer in SEG)" to "Komputer (Computer in SWG)"
While SWG is no longer official, it is still commonly spoken and taught in more rural areas, while more urban areas teach the "proper" SEG.
Slavic slang has entered in the German Vernacular as well. Compare the SWG "Arschloch! (Asshole)" to the SEG "Mudasch!"
Here is a language map, overlayed by an OTL Germany map.
(Forgive me on my shaky understanding of German Dialects, some changes are intentional, some are not.)