The difference between an epidemic and a pandemic is two-fold. First a pandemic is normally used to indicate a far higher number of people affected than an epidemic, and a pandemic refers to a much larger region affected. In the most extreme case, the global population is affected by a pandemic. An epidemic is defined by an illness or health-related issue that is showing up in more cases than would be normally expected. However, in the case of a pandemic, even more of the population is affected than in an epidemic.