Anything biographical has to do with the story of someone's life. If you're reading a biography of Margaret Mead, you might enjoy learning biographical details, like that she was the oldest of five children.
A biography is a book about someone's life. Anything biographical can be from a biography, as in an actual book about someone, or just facts from a person’s life. Biographical information could be where someone is from, where they grew up, where they went to college, or when they became famous. Biographies are usually written about famous people, but everyone has biographical details about their own lives, too.