What is the difference between a communist, capitalist, and socialist economy?

Capitalism: Almost everything exists as some form of privately owned capital

Communism : Society has organised itself into a system whereby everybody works as much as they can, and receives whatever they need.

Socialism: this is the transitional stage between capitalism and communism. The state organises the economy and society so that there are no more capitalists, and the workers run the place. Eventually it transitions to communism