Moral and Ethical?

I've never understood why people say "moral and ethical" as in "the moral and ethical implications of that action are serious." I've always thought the two words were synonymous making that phrase redundant, saying the same thing over again, and redundant. Is there a distinction I'm missing here? What is the difference between ethical and moral? Can an immoral act be ethically permissible, can an unethical act be morally necessary, or do they mean the same thing?