Babe is a word used to address a young woman, or your wife, husband or lover, usually expressing affection but sometimes considered offensive if used by a man to a woman he does not know. Now many people use it to refer to an attractive young woman, for example: she is really a babe.
French word "belle" means beautiful woman, hence, campus belle is the most beautiful girl in the school.
I feel that the meaning has changed a little after the translation.
校花 in Chinese means more than just "the most beautiful woman". She is pretty, popular, and she is well known in the campus. Girls envy her, boys admire her. She is the goddest that you will never get.
校草，sexually appealing man? I prefer emotionally.... He is handsome, usually with charming personality, maybe good at singing or dancing or play guitar... He has everything that girls dream about their Mr. Right.