Both modern and postmodern art represent a break from strictly or superficially representational art.
Modern and postmodern art both have roots in the 19th century. They hold a special place in the history of Western culture, contributing to the cultural and social upheaval in continental Europe that ultimately led to the conflict that began World War I. During this period, art was transmogrified from works that glorified or flattered wealthy patrons to expressions of private sentiment and cultural anxieties.
Media
While modern art represents a break from the classical art of previous generations, it still focuses on sculpture and painting. Postmodern art includes other artistic expressions based on novel technology like television and photography. It also incorporates multimedia presentations, such as performance art composed of acting, music and other visual arts. Both modernist and postmodernist movements are reactionary products of their time.
Politicism
While political comment, propaganda and criticism has always been a part of art, modernism and postmodernism make these themes explicit. Much of the officially sanctioned art of 20th century social experiment regimes are modernist propaganda, like Italian and Soviet futurism, which combined neoclassicism with recognizable glyphs and symbols to glorify ideology. Postmodernism is no less political but typically insists on criticizing oppressive regimes and ideologies, as seen in Pablo Picasso's "Guernica."
Avant-garde
The postmodern movement was largely facilitated by the development of new media technologies like film; this empowered many new artists to react unconventionally to the traditionalist schools of art, using elements like collage and mixed media to unsettle the observer. By contrast, since modernist artists were traditionally trained, their reaction to the traditionalists was confined to sculpture and painting. The new movements of surrealism, Dada and futurism tend to make the Impressionism of the Modernists look conservative.
Deconstruction
The Postmodernists owe credit to the Modernists for criticizing long held assumptions about the philosophical systems behind art. The typical postmodern reaction to art removes the idea that art should be formulaic, representative, technically skillful and, above all, generalized rather than personalized. The assumptions that Modernists made about meanings in art being blatant and easily decoded were violently rejected by Postmodernists.
