Of Mice and Men is a novella written by John Steinbeck. Published in 1937, it tells the story of George Milton and Lennie Small, two displaced migrant ranch workers, who move from place to place in California in search of new job opportunities during the Great Depression in the United States.
A diagram is different from an illustration because it is labeled and tells you information. From a illustration you have to analyze it and infer what it might mean.