The term "trademark" is often used to describe what are actually three categories of names; trademarks, service marks, trade names.
Trademark
A trademark is word, name, symbol, shape, slogan, color or even a smell that is used to identify a particular product. In order to qualify as a trademark, it must be used in connection with the product itself, and not in advertising, on business cards, letterhead or the like. In other words, a trademark must be either attached to the product or its packaging.
Service Mark
A service mark on the other hand, is used to identify services provided by a company. For example, consulting services, retail store services, programming services, engineering services, transportation services, etc. In the case of a service mark, it would be in advertising, on signs, on business cards, on letterhead or the like since there is no physical product to which the service mark can be attached.
Trade Name
If the name of a business does not qualify as a service mark because services are not being rendered, the business name is a "trade name."