What is the difference between a reheater and a superheater?

A reheater is essentially a type of steam superheater that heats the low-pressure steam that has already done work to reach a certain temperature. The function of a reheater is to further improve the thermal efficiency of the power plant’s cycle, as well as to keep the steam temperature at the final stages of the turbine within acceptable limits. A superheater is a heating surface in a boiler that heats saturated steam at a certain pressure into superheated steam at the same pressure. The component in a boiler that heats steam from its saturated temperature to a superheated temperature is also known as a steam superheater. Most industrial boilers are not equipped with superheaters, as many industrial production processes and domestic facilities only require saturated steam. In power plants, locomotives, and marine boilers, superheaters are generally installed in order to improve the cyclic thermal efficiency of the entire steam power plant. Using superheated steam can reduce the moisture content in the turbine exhaust. The temperature of superheated steam depends on factors such as the boiler pressure, evaporation rate, the high-temperature resistance of the steel used, and the cost ratio of fuel to steel. For power station boilers, those operating at 4 megapascals typically have a steam temperature of around 450°C; whereas boilers operating at pressures above 10 megapascals have a steam temperature of 540–570°C. A few power station boilers also use higher superheated steam temperatures (which can even reach 650°C).

What medium is used to reheat the low-pressure steam that has already been expanded in the reheater?