No, you're right, it doesn't.
There's the choosing of who is the government, dictatorship, democracy (split into different electoral systems), monarchs etc.
Then there's the -isms, like capitalism, communism, socialism, democratic socialism and the like which is the way the government is functioning.
These are two different things. The problem is that some people see the word "Communism" and they think "USSR", so all Communism must be the same as the USSR, even though the USSR wasn't very Communist. It was Socialist for sure.
But even Socialism and Communism are different types of things. You could be Socialist and not Communist. Communist and Socialist. Or Communist but not Socialist (perhaps, I haven't figured out how this would actually work).