Answer:
An iceberg can serve as a useful metaphor to understand the unconscious mind, its relationship to the conscious mind and how the two parts of our mind can better work together. As an iceberg floats in the water, the huge mass of it remains below the surface. Only a small percentage of the whole iceberg is visible above the surface.
I have written a similar essay. Except it was multiple pieces completed by two different artists. I would say start with the intro, then write the similarities in the second paragraph, the differences in the second paragraph, and the conclusion. If you need more paragraphs to reach requirements then do this:
1. Intro: give brief background to artwork and artist and write thesis
2. Similarities in technique
3. Differences in technique
4. Similarities in emotion conveyed
5. Differences in emotion conveyed
6. Conclusion: summarize comparison and rephrase thesis.
*no idea if this answers your question*