Anne Frank was known for her optimism, hunger for knowledge, and creativity. She could be moody at times, given the fact she was a young woman. However, she was extraordinary girl; an astute observer of both politics and human nature.
Margot Frank, in Anne's description, is more reserved. She's described as prettier, more grown up, and more of a "proper lady" than Anne. She aspired to be a maternity nurse in Palestine. It's implied that she's underappreciated, too.