sowjetisch
Soviet
Relating to the Soviet Union (USSR), its citizens, its politics, or its culture.
Die sowjetische Armee zog 1994 aus Ostdeutschland ab.
The Soviet army withdrew from East Germany in 1994.

Soviet
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Soviet
Relating to the Soviet Union (USSR), its citizens, its politics, or its culture.
Die sowjetische Armee zog 1994 aus Ostdeutschland ab.
The Soviet army withdrew from East Germany in 1994.

The adjective is derived from the Russian word 'Sowjet' (совет), which means 'council'. The ending '-isch' is a typical German ending for forming adjectives from nouns.
Das ist eine typisch deutsche Angewohnheit.
That is a typically German habit.
The adjective 'sowjetisch' (Soviet) almost always refers to the Soviet Union (USSR), a state that existed from 1922 to 1991. It is used for anything connected with that state.
Viele Gebäude aus der sowjetischen Zeit stehen heute unter Denkmalschutz.
Many buildings from the Soviet period are now protected as historical monuments.
'Sowjetisch' (Soviet) is often combined with nouns that refer to the state, the military, or culture, for example 'die sowjetische Regierung' (the Soviet government), 'ein sowjetischer Autor' (a Soviet author), or 'die sowjetische Raumfahrt' (Soviet space travel).
Der erste Mensch im All war ein sowjetischer Kosmonaut.
The first person in space was a Soviet cosmonaut.
The original meaning, which refers to the workers' and soldiers' councils ('Sowjets' — soviets), is very rare today. It is used only in specific historical texts about the Russian Revolution.
Die Machtübernahme durch die Bolschewiki basierte auf dem sowjetischen System der Räte.
The Bolsheviks' seizure of power was based on the soviet system of councils.
Russian
'russisch' and 'sowjetisch' can be confused because Russia was an important part of the Soviet Union. However, 'russisch' refers to Russia, the Russian language, people, or culture. 'sowjetisch' refers to the former Soviet Union, that is, a historical state with several republics. Not everything Soviet was Russian, and not everything Russian is Soviet. For present-day language, culture, or things from Russia, you normally say 'russisch'. For history, politics, or things from the time of the USSR, 'sowjetisch' fits.

Im Museum sieht man alte sowjetische Plakate aus dem 20. Jahrhundert.
In the museum, you can see old Soviet posters from the 20th century.
In dem Kurs lernen die Teilnehmer russische Wörter für den Alltag.
In the course, the participants learn Russian words for everyday life.