Arch Dam ;
Arch dam can be defined as a solid wall, curved in plan, standing across the entire width of the river valley in a single span. The body of arch dam is generally made of cement concrete. Thus, arch dam is just a curved beam, the ends of which are restrained and the way in which the loads are resisted is termed a arch action.
Buttress Dam ;
A buttress dam or hollow dam with a solid, water-tight upstream side that is supported at intervals on the downstream side by a series of buttresses or supports. A buttress dam envisages to reduce the total volume of concrete by constricting the material where the stresses are higher and other undesirable features of gravity dam but has higher cement content per cubic metre of concrete than a gravity dam.