"manners come from the heart to include people, as 'Do unto others as you' would have them do unto you'." (GfS)

"The basic meaning of manners is just that; the art of making others comfortable." (GfS)

Clearly GfS sees more diffeence betyween those ways of summarising "good manners" than I do, since he (or she) says the latter isn't about manners but about etiquette.