Whereas conventional businesses distribute their profit among shareholders, in social enterprises the surplus goes towards one or more social aims which the business has - for example fair trade, vocational training for disabled people, or environmental issues.
According to UK’s Social Enterprise Coalition, a business which generates more than 50% of its income from trading (or at least 25% for a start-up) and reinvest the majority of its profit to further its social or environmental goals can be classified as a social enterprise.