The bronchi are the organs through which air enters and exits the lungs. The bronchi and lungs are two separate organs, so inflammation occurring in the bronchi is not the same as inflammation occurring in the lungs. Thus, acute bronchitis is not pneumonia, but both conditions can exhibit similar symptoms, such as fever, coughing, and expectoration. So how do we differentiate between acute bronchitis and pneumonia? Clinically, when such symptoms appear, doctors usually recommend a lung X-ray. If the lung X-ray appears normal, or there is only an increase or thickening of lung markings, the doctor will diagnose acute bronchitis. If the lung X-ray shows imaging signs of inflammatory exudation or shadows, then the doctor will diagnose pneumonia.