What's the difference? Well, we could look in the dictionary and see what it says. Dictionary.com gives us a nice little starting point:
Morals, ethics refer to rules and standards of conduct and practice. Morals refers to generally accepted customs of conduct and right living in a society, and to the individual's practice in relation to these: the morals of our civilization. Ethics now implies high standards of honest and honorable dealing, and of methods used, esp. in the professions or in business: ethics of the medical profession.
I've always made an internal distinction between the two, but every time someone asks me to explain it I'm at a loss. I KNOW it in my head but the right words to describe the difference just aren't there.
As I was pondering the question earlier today, I had a thought, and there's a clue to that thought in the above definition. Notice that morals are placed in a societal context, but ethics aren't. To me, ethics are the standards that come out of the traditional Wiccan Rede, "An' ye harm none, do as ye will." If you aren't harming another being by your conduct, it is probably ethical. But boy, you better consider that idea of harm rather carefully. Harm can come in many forms, and affect the world in many ways. Morals, on the other hand, vary from one society to the next, from culture to culture. Also, morals are often used as a means of controlling the members of a society. They allow definition of a narrow range of proper behavior, and the provision for punishment or ostracism for going outside that range.
So it makes me roll my eyes when I hear narrow-minded individuals railing against such things as homosexuality, polygamy, out-of-wedlock births, and the ilk. I'm not part of a society that condemns such actions as immoral; I only would regard them as unethical if one party were exploiting another and thus causing harm. Perhaps this is where a lot of my live-and-let-live attitude comes from. If your behavior is ethical, I'm not too concerned with your morals; if it's unethical than it's probably immoral even by my lax standards.