Technically, capitalism is simply the application of capital in businesses. It's pretty much the factor that distinguishes it from feudalism or slavery. Consumerism is what people do in markets, and markets exist in virtually every economic system.<br />
As far as the USSR thing goes, it really wasn't communist. It was just a totalitarian regime with communist rhetoric. Kinda how the US is an oligarchy, but we still talk about freedom and democracy
Capitalism is an economic system in which trade, industry, and the means of production are controlled by someone. In a Republic the citizens are the owners of the capital to use or dispose of as the see fit. Under Communism, like the old Soviet Union, the Government owns the capital and the people are considered capital to be used or disposed of as it sees fit.
consumption is a constant in human life. It really transcends any particular -ism. We've merely emphasized it recently.