A former USSR citizen living in Belarus answers the question, "What does 'Soviet' mean in the term 'Soviet Union?" (bolding mine for emphasis)

“Soviet” means “Vlast’ Sovetov” (Power of People’s Councils or something like that). Initially, communists pretended they are going to give the ownership of the factories and the land directly to the workers, self-governed by local councils. Which actually never happened. In reality USSR functioned more like a feudal state with most of the population being slaves, where those seeking actual independence and self-governance would be quickly detained, called “enemies of the people”, probably tortured, maybe forced to incriminate their friends and families, judged by kangaroo court, later sent to Gulag or just shot(under Stalin). Or (after Stalin) just sent to psych ward or become an outcast.

Soviets (councils/committees) did form all over the country spontaneously before October Revolution after the fall of tsarism, but bolsheviks, despite their favorite populist slogan “All power to the Soviets”, quickly dismissed everyone who wasn’t a member of their Party. So, shortly after the revolution, power belonged to soviets as much as the current DPRK is “democratic”.

Becoming a member of the Communist Party was only possible after proclaiming total loyalty to the organization and you weren’t actually expected to discuss the orders coming from above, very much like joining Mafia. You weren’t expected to challenge the system but could choose to be co-opted into it, enabling career advancement. A true member of the Communist Party will watch news not to form his own opinions but rather to know what is the current political agenda set by The Party.

Russian is just a person who has(or had) Russian nationality. Of course, it would be nearly impossible to live in Russia during USSR without also being a Soviet citizen, but many escaped before or shortly after the October Revolution.

USSR was a multinational empire, so it was possible, of course, to be non-Russian Soviet citizen even if living in Russia.

https://www.quora.com/What-does-Soviet-mean-in-the-term-Soviet-Union-How-are-Soviets-different-from-Russians