Art Nouveau came first, as the name sugggests, in the last quarter of the 19th century, and Art Deco followed in the 1920s. Art Nouveau is characterised by flowing forms and symmetry, think Biba, the later wallpaper patterns of William Morris and the black and white drawings of Aubrey Beardsley. Art Deco was characterised by geometric forms and assymmetry - think bronze figures holding beaded table lamps and the bright oranges and blues of the pottery of Clarice Cliff.