If you have specific requirements to your particular writing task, I would pay attention to those in the process of writing the paper. I think that a compare and contrast essay on two paintings should feature some level of discussion about the motivation behind each painting as well as the background that gave rise to it would be a part of the assembling process. Being able to compare and contrast the growth and development of the painting would be important topics to explore. I believe that the techinical analysis of each painting in terms of style, technique, and aspects of artistic merit in each painting. This might involve points of convergence and divergence. Being able to explore these as well as how these elements are a part of the artistic tendencies of the artist would be part of the process of assembling a compare and contrast essay on the two paintings. I think that the last part would be able to explore the impact of the paintings on the artistic legacy and even examining critical reception of each. In this, I think that an entire composite is presented of both paintings in a compare and contrast manner.