Post-Impressionism is a term used to describe the reaction in the 1880s against Impressionism. It was led by Paul Cézanne, Paul Gauguin, Vincent van Gogh and Georges Seurat. The Post-Impressionists rejected Impressionism's concern with the spontaneous and naturalistic rendering of light and color.
Plot! Plot can change a movie and define its genre. For example, if the plot is in space and is about the future, then this would most likely be called a Sci-Fi movie. Hope this helps!