Not so easy. Pneumonia is an infection of the lung or lower respiratory tracts. A cold (usually caused by viruses) is an infection of the upper respiratory tract - flu also usually affects the upper tract but can start involving the lungs (serious). A patient should see a physician who can do lab tests and get an x-ray - doubly important to do so if a person is getting worse, dehydrated, or short of breath.
How do I know if I have a cold or flu? How can I tell if I got the common cold, influenze or pneumonia?
Flu worse than cold. A "cold" is an upper respiratory infection. It is usually associated with a stuffy nose and sometimes other symptoms related to that (post-nasal drip leading to cough, headache due to sinus congestion, etc.) a flu has an associated fever (increased body temperature), muscle aches, feeling bad all over. Pneumonia means you have a bacterial or viral infection in the lung. Read more...