The differences and similarities between personal and professional ethics can be tricky to pin down. Some people define personal ethics as conscience and professional ethics as a standardized code; by these definitions, a person can be torn between conflicting ethical beliefs. Others define ethics, in general, as moral guidelines and say that personal and professional ethics are just different ways to apply a single moral code. By that definition, they are much less likely to conflict.
Personal Ethics: Conscience
Some people use the term "personal ethics" to describe their own moral code -- the values and standards by which they operate in their daily lives. These can include honesty, accountability, loyalty and treating others fairly or kindly. A woman who visits her boyfriend at work and notices that he is spending company time playing computer games might feel that she is ethically bound to keep this secret out of loyalty to him. She also may feel that she is ethically bound to talk to him about his behavior in private if she believes that his actions are wrong. These are examples of personal ethics.
Professional Ethics: Code
If personal ethics are the dictates of an individual's conscience, then professional ethics are the individual's commitment to follow a particular code of behavior that is defined by his profession. If the woman is not the man's girlfriend but rather his co-worker, then her professional ethics might dictate that she bring his misuse of company time to the boss's attention to maximize benefits to the company. Her personal ethics may still be against jeopardizing his position, but her professional ethics may require her to take action. Personal and professional ethics, by these definitions, can conflict.
Personal Ethics: Private
Another definition for "personal ethics" is an individual's code of behavior toward the people around him and the efforts he makes to be the best person he can be in his private life. A man may have specific ideas about how much it is acceptable to drink when he is out with his friends. He may make this decision based on his knowledge of his own behavior when he drinks, his knowledge of his friends' level of comfort with his drinking and how his drinking may impact his productivity the next day. These are all considerations of personal ethics.
Professional Ethics: Work Life
In that case, professional ethics are an individual's efforts to be the best person possible in his work life. It may be personally ethical for the man to have two drinks with his friends, but it may not be professionally ethical for him to have the same two drinks before coming to work. He would not be violating any personal codes about drinking; however, any level of intoxication would be inappropriate in a professional context. His value system has not changed, but, because of the context, the way he implements it has changed. While his personal ethics are more general, his professional ethics are his applications of that moral code in a specific area of his life.