You can have professional ethics, but you seldom hear about professional morals. Ethics tend to be codified into a formal system or set of rules which are explicitly adopted by a group of people. Thus you have medical ethics. Ethics are thus internally defined and adopted, whilst morals tend to be externally imposed on other people.
If you accuse someone of being unethical, it is equivalent of calling them unprofessional and may well be taken as a significant insult and perceived more personally than if you called them immoral (which of course they may also not like).
Dictionary.com defines ethics as:
A theory or a system of moral values: “An ethic of service is at war with a craving for gain"
The rules or standards governing the conduct of a person or the members of a profession.
Ethics of principled conviction asserts that intent is the most important factor. If you have good principles, then you will act ethically.
Ethics of responsibility challenges this, saying that you must understand the consequences of your decisions and actions and answer to these, not just your high-minded principles. The medical maxim 'do no harm', for example, is based in the outcome-oriented ethics of responsibility.