Preludes and Rhapsody are similar in the sense that they portray a monotonous lifestyle. Prufrock is a bit different because Eliot talks about the modern man's insecurities resulting in societal detachment.
You wouldn't want to be discussing preludes and rhapsody together if you had a choice in the HSC to choose your poems unless the question is heavily geared towards monotony of life. Then you would more or less have very similar analysis for the 2 poems.
