East Berlin had trams, West Berlin had double decker buses. The doubledeckers can't pass safely below the wires of the tram, so if you see a tram you are in former east Berlin, but if you see a doubledecker you are in former west. At least that's what my friend told me years ago who lived in Berlin for some years. Can someone confirm this? I can't find any info on this on the internet.
As an east Berliner we have trams and no double deckers, but I have only seen double deckers near the center of the city.
I can't remember seeing them in the places with trams, but I don't see them much at all. This is my limited observation, as I don't use busses as much as trains and don't know the west as well as the east.
If you really care I can cycle out (in?) on the weekend and check.
The West adopted the goal of a prosperous population of car-owning motorists and dismantled their tramway system as the US did. The communists kept public transport as a norm (they had the Trabant, but it was mostly a showpiece, out of reach of the average citizen). Some time after the wall fell, opinion in the west shifted in favour of reestablishing tram networks (the Grüne party had a campaign in Berlin with activists pedalling “trams” made of bicycles in areas they wanted the tram routes extended to.
Actually the shift started with the oil crisis. That stopped most tram demolition and ended up with west German cities improving their tram systems with tunnel sections, new lines, better trams and so forth. You can see that in the number of old tram systems in West Germany, besides having closed a lot of them. As a comparison in 1980 France had three operating tram systems, the UK had one and Italy five.
Also the car free sundays had a massive cultural impact leading to pedestrian zones. Also the demolition of buildings for wider streets was mostly stopped. It also saw quite a lot of cycling paths being added.