COPD is a chronic progressive disorder. Classically, COPD is divided into 2 subsets: chronic bronchitis (blue bloater) and emphysema (pink puffer)

Chronic bronchitis is chronic cough with sputum production for at least 3 months for 2 consecutive years caused by chronic inflammation, which leads to narrowing of the bronchial airways.

Emphysema is characterized by the destruction of the the alveoli, which leads to impaired outflow of air and lung trapping