Differentiate between professional ethics and personal (or public) ethics.

Most professions come with a written code of ethics. A
professional code of ethics governs individuals' conduct within their profession so that
their behavior is ethical, honest, and above reproach. A professional code of ethics
also focuses on social issues and outlines the general principles which guide a company
or an organization's beliefs.  This code may be further broken into subcategories such
as "code of conduct" and "code of practice."  These are more specific "rules"
delineating to what standards employees or organization members will be held when it
comes to carrying out professional responsibilities.

On the
other hand, "personal ethics" or the public's ethics could more
simply be defined as a general standard of acceptable conduct within a society.  While
there exist specific written laws that individuals within a society will be held
responsible for following, laws do not necessarily determine the ethics of the public. 
More often, public ethics could be considered the general and mutual consideration for
what is acceptable behavior within a society.  In this way, public ethics vary greatly
between nations, states, cities, and even individuals.

To
paint a hypothetical picture that directly contrasts where professional ethics and
personal ethics could come into conflict, I think of the legal profession.  Lawyers (who
are governed by the bar) are bound by a professional code of ethics dictating specific
rules for how they must serve their clients.  Additionally, all alleged criminals are
given the "right to a lawyer."  A lawyer who, for example, is appointed to defend a
certainly guilty offender in a court of law, may face a conflict between his
professional code of ethics (which says that he must provide
adequate defense) and his personal ethics, which typically condemn such members of
society.