Final answer:
Chronic bronchitis is characterized by excessive mucus production in the bronchi, while emphysema involves alveolar destruction. Both conditions are part of COPD.
Step-by-step explanation:
Chronic bronchitis is characterized by excessive mucus production in the bronchi, the air passages that conduct air into the lungs. This excessive mucus can obstruct the airways and make breathing difficult. On the other hand, emphysema is associated with alveolar destruction, which leads to reduced elasticity of the lung tissue and difficulty exhaling air. While both conditions are part of the broader category of chronic obstructive pulmonary disease (COPD), chronic bronchitis specifically involves mucus overproduction.