Often when we are hear about the government of the USSR people like Stalin, Khrushchev, Brezhnev, etc. are portrayed as an absolute dictator of sorts.
However, when I read about the USSR whether it be in fictional stories or history on the nation you get references to things like the politburo who sometimes sound like they are the real decision makers in the USSR.
So how was the government of the USSR structured? Did the politburo have different political powers than the General Secretary? Who was the official head of state (if there was any)?
After the revolution there was a politburo, some thing like a council, however after Lenin died, there was a sort of an election for the next party leader, where Stalin won, after that there became such things as head-secretary, where in truth most of the power was always in the hands of the head of the party. Near the fall of the USSR a position such as the present of the Union was established, the last one being Gorbachov, and Yeltsin was the president of the Russian Soviet Socialistic Republic(RSSR). Also there were a lot of ministries both on the republic level, and the Soviet level, something like The Federal government, and the state, in Usa for example. In short the most important position was the leader of the party, official titles were just formal, nothing more.
Sometimes, both most of the time, the current head would choose people close to him to succeed him. For example Gorbachev was "chosen" as a younger generation leader by the politburo, because the previous 2, Andropov and Chernenko were too old, and died after a few years in office. Also it worth mentioning that there was a lot of behind the curtains power struggle for such posts, and usually the translation of power was done, for pack of a better comparison like a mentor to student. This is in general how it was, and very very oversimplified.