The assignment content discusses the periods of Impressionism (1870-1890) and Post-Impressionism in art history. Impressionist painters, such as Claude Monet and Edgar Degas, focused on capturing light and color in their works, while Post-Impressionist artists, like Vincent Van Gogh and Paul Gauguin, emphasized expressing emotions through their paintings. The two periods share similarities in terms of breaking away from traditional academic painting styles, but also have distinct differences in terms of the level of emotional expression in their works.