What is the difference between personal and professional ethics?

The difference concerns the moral position or status of the moral agent. In western philosophy since the days of the ancient Stoics, the dominant view has been that all human beings are morally equal, in other Words, of intrinsic and equal worth. A human life is inherently valuable, and no human life is more or less intrinsically valuable than another human life. Adopting the moral point of view is often equated with this view. However, this doesn't mean that all humans are equal; it only means that all humans are intrinsically equal in terms of their moral worth. They are unequal in many other respects. In some circumstances, some people have power over other people. For example, a therapist has more power than a patient. In a situation in which people are not equal in terms of their power, it may be important NOT to treat people as if they were morally equal. Ordinarily, while it might be acceptable for someone who happens to be a therapist to ask another person for a date, it would not be acceptable for a therapist to ask a patient for a date (because there would be unusual pressure on the patient to accept due to the patient's status in therapy). That shows the difference between personal ethics and professional ethics. Personally, it may be true that we are all morally equal. Professionally, however, that is not true, and that inequality of condition deserves special consideration. That is why personal ethics may differ from professional ethics.