You have to think of it as a political spectrum. Comunism on one side and socialism on the other (america today being somewhere close to the middle). Communism is the idea that everything and everyone are equal. Everyone gets the same pay, same food rations, etc. This would mean that there can be no government to instruct the people. However, in order for communist ideas to happen, a leader or group of leaders would be needed to distribute the supplies to the people and hand out the pay. This goes against true communism, which would mean 0 government, and that is why it cannot really happen. In Russia, communism failed because the government took control of the country and abused its political power. Russia was more of a facist society, almost communist, but they still had government to control everything.
Hope this helps