One of the biggest differences between capitalism and democratic communism is how a firm is run. Unlike state communism, or "communism of the parties," which places control of firms in a closed, self-selecting Communist Party, democratic communism encourages active worker management of firms, to smash the position of authority and control that the owners of capital have over their workers, and to prevent a communist party from simply becoming bureaucratic capitalists.
Most firms will receive their capital from the government, and the condition the government requires is that firms are potentially worker-managed. When starting, a firm must have a charter, a set of by-laws as to how the firm is managed and who manages it. There can be a lot of flexibility, but the government imposes two requirements on the charter: first, if two-thirds of the workers in a firm so vote, the charter can be amended or replaced, and second, workers may not under any circumstances be prevented in any way from organizing and persuading their fellow workers to amend or replace the charter. An individual or group can run a firm as a "dictatorship" or an "oligarchy" so long as more than a third of the workers consent. The government encourages, but does not require firms to be actually worker-managed. Workers are never dependent on a firm for survival: they can always go to the government for a job that pays a living wage, and they have equal access to capital to start their own firms. Workers have the fundamental power; an entrepreneur can become rich only if she runs a successful business and persuades her workers, either directly or indirectly, to allow her to become rich.
As in capitalism, firms pay rent for their capital. However, this rent typically goes to the democratic government, to be allocated as the people, not the privileged capitalists, see fit.