Essentially the same as the change to socialism. There are many different brands of both communism and socialism, even different ideas of what the words mean.
In a communist country the government owns all of the property and gets all of the money from the sale of goods. They are supposed to take care of their people based on their needs. The down side is the leaders get to decide what people need. If they think the people "need" a massive military expense more than they need food, that's the way it goes.
Here is a simple comparison chart of political theories, including communism, socialism, populism, capitalism, etc. It answers questions like who controls the government, who controls production, and who controls goods, etc. http://www.bookrags.com/research/comparison-table-of-political-theor-ptfs-01/
You can find more detailed articles on all the political theories at wikipedia.org.