Mores are the customs, norms, and behaviors that are acceptable to a society or social group. If your personal morals are in disagreement with local mores, you should be prepared to be annoyed every time you read the local Letters to the Editor.
Mores and morals have similar meanings — mores are the morals of a group or society itself. They are not necessarily based on written law and they can change. The mores of the Victorian era prescribed modesty for women. A Victorian traveling to our time would probably be shocked by current mores that allow women to wear shorts.