Which of the following is the most significant difference between emphysema and chronic bronchitis?

A barrel chest is less common in emphysema than in chronic bronchitis

The damage of emphysema occurs in the alveoli while the damage of chronic bronchitis occurs in the airway

A productive cough is an early sign in emphysema while chronic bronchitis is characterized by cough later in the disease

Cyanosis is common in emphysema and less common in chronic bronchitis