In the play Riders to the Sea, Cathleen and Nora are sisters, and they share points of both comparison and contrast.

Cathleen is the older of the two, and she is a practical young lady, capable and responsible. She makes arrangements for her family, preparing for her brother Bartley to go to sea even after learning that her other brother Michael has drowned. Cathleen hides Michael's clothing from her mother, Maurya, until she can make sure it truly belongs to Michael and figure out how to tell her mother that she has lost yet another loved one to the sea. Cathleen has little patience with her mother's “superstitions” and laments and visions, and she fails to sympathize with Maurya in her grief. Cathleen supports Bartley's desire to go to the fair even if that means crossing the sea, and she is annoyed by her mother's attempts to stop him. Cathleen appears to be a young woman who buries her emotions and focuses on what needs to be done.

Nora is a young girl at the time of the play, and she helps her sister around the house, taking care of their mother and learning from Cathleen's practicality. She assists Cathleen in hiding Michael's clothing, and she supports Bartley's desire to go to sea. Yet Nora is much more trusting, sympathetic, and patient than her sister. She believes the priest when he tells her that no harm will come to Bartley, for God will not leave her mother without any sons. But of course, the priest is wrong, and Bartley is thrown from his horse and dies. Nora pities and sympathizes with her mother when Bartley dies, and she kindly and respectfully gets holy water so that her mother can sprinkle her brother's body. Indeed, Nora is kinder than Cathleen and seems to understand her mother and her mother's grief better than her sister does.