Strictly speaking, a greenhouse is heated only by the sun, while a hothouse has an artificial, or supplementary, source of heat. The terms are often used interchangeably, even by professionals. In reality, a greenhouse becomes a hothouse during cooler seasons, or when artificial heat sources are necessary to keep crops healthy. By contrast, in warmer climates, during the heat of summer, some form of cooling is needed in order to maintain a consistent temperature.
For temperature and moisture control, agricultural producers typically install fans, vents or shutters not only to control heat buildup but also to help with moisture control. One of the primary advantages of greenhouse growing, or "controlled environment agriculture" is that conditions can monitored and adjusted as needed, and growers need not be totally dependent on favorable weather conditions for crop growth.
