Many of the symptoms of the cold and influenza are similar and it can be difficult to distinguish between the two at times, but influenza is often a more serious disease.
Influenza usually starts off with a significant fever and feelings of fatigue and malaise. Other flu symptoms include a runny nose, sore throat, muscle pains, headache and coughing.
The flu is caused by any of a number of influenza viruses.
The disease normally clears in a couple of days but sometimes causes complications like viral pneumonia, secondary bacterial pneumonia, sinus infections, and worsening of previous health problems such as asthma or heart failure.
Differences between the Common Cold, Nose Allergies and Sinusitis
Reference:
Wikipedia Influenza.
