Intaglio
Intaglio is printing from the recessed areas below the surface of a metal plate or other substrate (i.e. copper, zinc, aluminum, plastics or even coated paper) — and is distinguished from relief printing which is printing from the areas above the surface. Images are cut, scratched or etched into the plate or printing surface, viscous ink is rubbed into the incisions or grooves, and the surface is wiped clean. Using a roller press to print, wet printing paper is embossed with considerable pressure into the incised lines or recessed areas of the plate. Various intaglio techniques include engraving, etching, drypoint, aquatint, and mezzotint which can produce a wide range of visual effects.
Relief
In contrast to intaglio, relief is printing from the areas raised above the surface of a block, plate or other substrate (i.e. wood, linoleum, aluminum, zinc, magnesium and plastic). Areas not to be printed can be cut or etched away to leave the design standing in relief — or, instead of cutting away the background, a relief can be created by building upon the surface. The surface is inked using a roller or a dabber, a sheet of paper is placed on top, and pressure applied by hand or using a printing press. Common types of relief processes include woodcut, linocut, and wood-engraving. Relief and intaglio processes can sometimes be combined by first applying ink to the depressions (intaglio) and then rolling the raised surfaces (relief) for interesting visual effects.