Profession and Professional

A profession is a specialized work function within society, generally performed by a professional.

In a more restrictive sense, profession often refers specifically to fields that require extensive study and mastery of specialized knowledge, such as law, medicine, nursing, the clergy or engineering. In this sense, profession is contrasted with occupation, which refers generally to the nature of a person's employment.

A profession is always held by a person, and it is generally that person's way of generating income. Some historians believe that the foundation of modern civilization is division of labor into different professions, thus increasing the level of expertise held by professionals.

Professional

Definition: Of or pertaining to a profession, or calling; conforming to the rules or standards of a profession; following a profession; as, professional knowledge; professional conduct.

A person who prosecutes anything professionally, or for a livelihood, and not in the character of an amateur; a professional worker

A person engaged in one of the learned professions

The distinction between laypersons and professionals denotes the critical aspect of more liberal definitions of a profession: being paid for the work. As such, ball players and movie makers may be professionals, although their work does not fit the strict definition offered above.

Sources:
Ethics in Information Technology by George Reynolds (2006)
http://en.wikipedia.org/wiki/Professional
http://www.qualityresearchinternational.com/glossary/profession.htm
http://en.wikipedia.org/wiki/Profession