What’s the difference between ‘Miss’ and ‘Ms’?
Miss is a title for an unmarried woman or girl, especially one under the age of about 30 (e.g., ‘Miss Jones’). It cannot be used for a married woman. It is sometimes seen as slightly old-fashioned, since it defines the woman by her marital status.
Ms is a title for a woman whose marital status is unknown, for an older unmarried woman, or for any woman in a context where you don’t want to emphasise the woman’s marital status. It’s intended to be neutral, in that it can be used for married and unmarried women alike – much like ‘Mr’ can be used for married and unmarried men.