What are the differences and similarities between Catherine and Myrtle in The Great Gatsby?

Catherine and Myrtle are sisters. Catherine is unmarried and lives in New York City and Myrtle is married but involved in an affair with Tom Buchanan. At the party in Catherine's apartment (Chapter 2), Catherine tells Nick about all the wonderful places she has visited. This scene establishes Catherine as a character who is adventurous and easily bored. Similarly, Myrtle frequently complains to anyone who will listen about her husband Wilson, a near-blind auto-mechanic who lives with Myrtle outside of the city. Therefore, Catherine is similar to Myrtle (who frequently leaves her boorish husband in order to fraternize with the more exciting Tom Buchanan) because they both are unsatisfied with their lives and are searching for something more. However, they are different because Catherine repeatedly proves to be the more conscientious of the two, for she provides the apartment in which Myrtle conducts her affair (thereby saving her sister's reputation) and rushes to Myrtle's aid after Tom breaks her nose during the fight in that same apartment.