A cold is an upper respiratory infection caused by a virus. Symptoms of a cold usually include a runny nose, sneezing, coughing, sore throat, muscle aches, headaches, low grade fever and congestion of the ears, nose and head.
Colds usually last for a few days, but symptoms can persist for weeks.
The flu is caused by a set of viruses which occur in epidemics during the winter. Symptoms are similar to a cold, but tend to be more severe. A flu usually has a sudden onset and lasts 1-2 weeks. The general body symptoms of the flu, such as fever, body aches, and malaise, tend to be stronger than the respiratory symptoms. Complications are uncommon in young, healthy people but may include pneumonia, bronchitis, ear or sinus infections.