Corporations make money for people who do not work at the company, and do not work for the company. The people who pull in the profits are shareholders-- outside investors who own shares in that company. At a corporation, workers are paid a fraction of the value of their labor.

Co-operatives make money for the people who work directly in that store, at that company. There are no outsiders who pump the profits away from the workers. At a co-op, workers are paid close to the full value of their labor.