First of all, resources are what you need to make goods and services.
             In Capitalism, private property (resources) are admitted, but in Communism, all the resources are under government's control, so nobody is allowed to use any resources, such as land, labor, and capitals.
             Secondly, since there's no private resources are allowed, there won't be any entrepreneurship in Communism. Only government produces goods and services in Communism. In Capitalism, the entrepreneur exists. People have right to use their own property, and resources, so they become the entrepreneur of what he make.
             Thirdly, there is no greed or invisible hand in Communism. Nobody is allowed to have their own resources, so nobody can greed anything, only the government has everything, and the government decides the price, and since there's no entrepreneur, there won't be any competitor of certain products. In Capitalism, greed exists, and with enough resources it's possible for competition between companies in capital society, so the invisible hand will decide the price.
             Fourthly, in Communism, only government is the one big company, their supply is limited since the resources are limited, and even though the demands of certain product increases, the supply will remain same. In Capitalism, the market decides the supply and demand. If the demand increases, the supply increases too, and if the demands are low, the companies decreases the production of the goods.
             Fifthly, the emphasis on personal economic freedom in Communism is very rare. They don't own any properties, and they can't decide the price or the quality of goods or services. In Capitalism, once again, people have right to use their own property, like money. They can but whatever they want to buy, and they can make anything they want, so in order to increase the demands, the company makes better quality and services to make buyers to spend...