How are bacterial pneumonias different from viral pneumonias?

Cause and treatment: The cause is different. Viruses are much smaller than bacteria, harder to identify, and are treated with an entirely different kind of medications. Treatment for one does not work for the other.

Differ in many ways: Viral & bacterial pneumonias differ in many respects other than the causative agent. Their symptoms can overlap with both causing fever, cough, shortness of breath etc. They can be differentiated on basis of some blood tests, cultures of respiratory secretions & chest xray. It is also important to remember that some illnesses that start as viral illness can develop secondary bacterial infection.

Difficult: Often very difficult to distinguish. However, bacterial pneumonia is more likely if the patient is very sick.