I subscribe to the view that "morals" applies to individuals and "ethics" applies to social structures. I learned this distinction in graduate school from Louis Dupré, who described it as the Hegelian view. I know other people distinguish morals and ethics differently, but this distinction makes the most sense to me.
It is often hard in teaching sociology to individualistic Americans to give a clear example of the distinction between a whole bunch of individuals and a social structure. A good society, they figure, is just the sum of the actions of a bunch of good individuals. But social structures, I try to show, have values embedded in them that serve the institution's ends, regardless of the morals of the individuals acting within them.
Most Americans who study Robert E. Lee find him to be an admirably honorable man. I do, too. And nearly all Americans now see slavery as a great evil.
Yet Lee fought for slavery.
Without a distinction between individual morals and structural ethics, most Americans are left morally dumbfounded, caught between their two opposing judgments.
"Robert E. Lee had good individual morals but served a bad ethical structure" is a teachable case that I believe most of my students will find helpful.