Published by a university press, or a scholarly society, or an academic series by a trade publisher (e.g. Jossey-Bass Higher and Adult Education Series).
The author often has an academic affiliation and is a recognized authority on a topic (e.g. a professor at a university).
The work includes an extensive bibliography or list of works cited and an index to topics covered.
Published by a trade publisher such as Random House and intended for a broad audience, not just those studying in that discipline.
The author may have a corporate or business affiliation instead of an academic affiliation.
The author may include a bibliography and index, but they are less extensive than for scholarly books.
TIP: In academic research there is a clear preference for refereed or scholarly material. However, there is also a role for non-scholarly material since it often reflects contemporary thought and is popular. Also, there may be little scholarly material available on a given topic. If you use sources such as newspapers or popular magazines, clearly point out that your information reflects a "commonly accepted position" but is "difficult to verify or refute".