I refer to this difference many times in the series.  Morals refers to how we SHOULD act; Mores (The singular is Mos; it comes from Latin) Mores refers to how a society actually DOES act.  Our Mores usually fall short of our Morals.  For example, we SHOULD study the Catechism.  Among MANY Catholic men, the Mos by which they actually live says, "Real men don't do that; that's for women", or, "I don't see any other men doing that; if I do it other men will think me odd". 

            or the following case.  The 6th commandment requires that one should observe custody of the eyes.  That would be under Morals.  But the mores kept by many American men today say, - "Looking at Internet porn - or reading magazines like Playboy - or sneaking looks at women other than my wife - show that I am a red-blooded man".