Stucco basically refers to a coating for the outside of a building and plaster to a coating for interiors.. It is used as a garnishing coating for walls and ceilings, and as a sculptural or artistic material in architecture. Stucco can be used to cover less visually appealing construction materials, such as metal, concrete, cinder block, or clay brick. Stucco is a tough, tempting, and weather-resistant wall covering.