The Chartered Institute of Public Relation’s (CIPR) code of ethics is much more spelled out then the codes of ethics for the Public Relations Society of America (PRSA) and the International Association of Business Communicators (IABC). There are many paragraphs explaining how to prosecute one who is in violation of the code. I assume that there have been many cases in which the interpretations of the code have varied which have led to controversy. Writing a detailed code avoids a great deal of that kind of mess.
The IABC code of ethics has a much more business minded approach. IABC’s code uses lots of words like "legal" and "timely." I believe that this is due to the fact that this code was written by business professionals that ended up in communications, hence the BC in IABC.
PRSA’s code seems to have integrity closer to the heart than the other two. It is brief and has a feel of, "you know what you should do." I think this is why this code of ethics is held as the standard for public relations.
However, fundamentally these codes come from the same place. They all put great emphasis on honesty and accuracy.