Well, for me, it's the difference between "morality" and "ethics." Ethics are... slightly different -- morality is based heavily on personal and familial beliefs. For my money, morality is something we've had instilled in us (or not) from an early age.

For instance, I had a student want to argue that abortion was immoral -- but there's no quantifiable evidence to prove or disprove the morality of abortion. You can't measure morality, you can't cite it, and because morality itself is so subjective, and individuals have different moral compasses, it's difficult if not downright impossible to present a coherent argument, possibly because it's more an emotional argument than anything else.

Granted, morals and ethics do cross paths, and while it's sometimes easy to point to unethical behavior and say "That's immoral," it's not always so black and white.