Pretty and sexy are very different. Sexy can have a bad connotation where pretty is a socially nuetral term for saying someone looks attractive. Sexy tends to refer more to vanity...a sexy person makes an effort to attract attention where a pretty girl is attractive naturally. Sexy usually implies a more scandelous choice in clothing, where pretty refers to looking nice in everyday clothing. A mother or father could call their daughter pretty, but never sexy. That would be inappropriate. Sexy is like music videos and the dance club. Pretty is your mother, a little girl with a bow in her hair, or a nicely wrapped birthday gift.