The difference between an online service and a bulletin board service is one of scale and profits. Online services provide a variety of information and services, whereas BBS's normally concentrate on a single theme. In addition, BBS's are often operated on a non-profit basis whereas online services are always for profit. Three of the largest online services are America Online, Compuserve and MSN.

One online service that defies classification is the Internet. In terms of users, it is the largest service, but it is not centrally controlled by any one organization, nor is it operated for profit.