The difference between a customer and a client can at first seem quite confusing. Some people say there is not much difference, while others say it depends on the industry as to whether the term "customer" or the term "client" is used for business patrons. However, the difference between a customer and a client can best be seen in terms of an ongoing business relationship.

According to the American Heritage Dictionary, both "customer" and "client" can be defined as "one that buys goods or services." However, the Dictionary lists only the one definition for customer, but has five other definitions for client. A client is also defined as "the party for which professional services are rendered, as by an attorney" and as "One that depends on the protection of another." The main difference between a customer and a client is that a protective, ongoing business relationship is formed with a client, but not necessarily with a customer.

Word origins also show the difference between a customer and a client as the client relationship being one of a dependent business person needing protection. For example, the origin of the word "customer" dates back to the Middle English of the 1400s and is related to the word "customs" as ways of doing things. The word "client," on the other hand, was also a part of Middle English vocabulary, but it dates back even further. "Client" is derived from the Latin word cliens which means dependent or follower.

The difference between a customer and a client is that a customer can be just a patron, while a client is a patron who also seeks advice. In today's business world, we don't just have customer service, but we have "client care" or "client service" departments in many corporations. Most patrons of a business want to be informed, but those who depend on their relationship with a business such as a client with a lawyer, need a protective type of informative business relationship. A client looks to follow the advice and professional knowledge of a business leader, while a customer may only purchase goods and services from a business.