Pneumonia.... ..Is an infection and pulmonary edema isn't; pe usually happens because of a cardiac failure.
Fluid versus infect. Pulmonary edema is fluid in the lung from any cause, sometimes related to impaired heart function, but also seen with a number of other causes of inflammation in the lung, such as smoke inhalation, trauma, and severe infections including pneumonia. Pneumonia is a lung infection. The two entities can coexist and may look similar on chest xray.