Hot flashes are a sudden but brief sensation of heat all over the body, which is usually considered as one of the common symptoms of menopause. At a particular age in women's life, an average woman will experience certain physiological changes that will put a stop to her monthly menstrual cycle. This condition is known as menopause, and it is usually confirmed when a woman stops menstruating for a complete 12 months. Hot flashes are part of the symptoms of this stage, and can also be experienced during the transition stage.
A fever, on the other hand, has so many causes, and it is a common symptom of so many health conditions. It is usually confirmed by a temperature higher than the normal body temperature. The normal body temperature is put at 37°C, though the human temperature can change, and it is never constant throughout the day. However, one can be said to have a fever if his temperature is equal to or greater than 38.3°C. Hot flashes are only experienced by women who have reached menopause, but fever can be experienced by anybody.