In a sense, both the dam and reservoir are constructed to serve the same purpose, at least they prevent the flow of water. However, there are some differences between the dam and the reservoir. A dam is a structure placed across a flowing body of water so as to stop the flow. Dams are mostly constructed in such a way that they won’t be able to control the flow of water after it has reached a particular height.
A reservoir, on the other hand, can be defined as a man-made lake where water is collected and kept for use any time it is needed. From the two definitions, it is evident that a dam is just a physical structure constructed in the form of concrete across a flowing body of water to prevent the flow of water. While the true meaning of a reservoir is centered on the water behind the walls constructed. Dams are often used to generate electricity, while reservoirs are made for domestic needs.