Influenza: What is the difference between a cold and flu? What is the difference between COVID-19 and the flu?
Influenza (flu), the common cold, and COVID-19 are contagious respiratory illnesses, however, are caused by different viruses. Flu is caused by influenza viruses only, whereas the common cold can be caused by a number of different viruses. COVID-19 is caused by infection with a coronavirus first identified in 2019.
Because flu, the common cold, and COVID-19 have similar symptoms, it can be difficult to tell the difference based on symptoms alone. Testing is needed for proper diagnosis. Testing is also important because it can reveal if an individual has both the flu and COVID-19 at the same time. More information can be found here and here.