Bronchitis is inflammation of the breathing tubes. These are the airways called bronchi. This inflammation causes too much mucus production and other changes. Although there are several different types of bronchitis, the most common are acute and chronic. Chronic bronchitis is long-term inflammation of the bronchi. It is common among smokers. People with chronic bronchitis tend to get lung infections more easily. They also have episodes of acute bronchitis during which symptoms are worse.
Emphysema is a chronic lung condition in which the air sacs (alveoli) may be destroyed, narrowed, collapsed, stretched, or overinflated. Overinflation of the air sacs is a result of breakdown of the walls of the alveoli. It causes a decrease in respiratory function and breathlessness. Damage to the air sacs is irreversible and results in permanent "holes" in the tissues of the lower lungs.