I don't see them as similar. Miss marple is a life-long spinster,very quiet, happy with who she is and enjoying observing people and solving little puzzles.
I can't imagine her getting into the situation julie is in. Julie has been browbeaten all her life into thinking she's not good for much and needs others to make decisions and take responsibility for her, by first (I guess) her family, then her husband, now that her husband is gone, others in the community trying to take over that role. At rthe moment, she is realizing that this is the case and she can change it, but of course, it's not going easy. She is blundering around, reacting to events, trying to find her way.