Catarrh and phlegm are both related to the production of mucus in the respiratory system, but they are not the same thing.
Catarrh refers to inflammation and excessive mucus production in the nasal and sinus passages, which can cause symptoms such as congestion, difficulty breathing, and a runny nose. Catarrh is typically caused by infections, allergies, or irritants.
Phlegm, on the other hand, refers to the thick, viscous mucus that is produced in the lungs and lower respiratory tract. Phlegm is typically associated with conditions such as bronchitis, pneumonia, and asthma, and it is usually expelled through coughing. Phlegm can be clear, white, yellow, or green and its color can be an indication of the type of infection or irritation.
In summary, catarrh is inflammation and excess mucus in the nasal and sinus passages while Phlegm is thick, viscous mucus produced in the lungs and lower respiratory tract.