What's the difference between a mirror girl and a prophet?

Different functions; Different authenticity, etc.

Different roles: Mirror girls usually have special abilities in stories, such as predicting the future or other supernatural abilities. Their main function is to help the protagonist collect information and guide the protagonist to solve problems; Prophets use their claimed supernatural abilities or wisdom to provide guidance or predictions for people. Their role is to predict the future based on astrology, divination, intuition or other verifiable methods.

Mirror girls are usually fictional characters, mainly appearing in literature and film and television works; The prophet is real. They claim to be able to predict the future and provide guidance or prediction for people.