Stucco is a construction material made of aggregates, a binder and water. Stucco is applied wet and hardens to a very dense solid. It is also used as a decorative coating for walls and ceilings, external building siding, and as a sculptural and artistic material in architecture. Stucco may be used to cover less visually appealing construction materials, such as metal, concrete, cinder block or clay brick and adobe.
But stucco sometimes refers to a coating for outside of a building and plaster to a coating for interior; the material itself is little different.