What is the difference between chronic airway obstuction and copd?

Difference... COPD is chronic obstructive pulmonary disease and it is one entity that causes chronic obstruction. There are other diseases that cause chronic obstruction so chronic obstruction is the more general category that COPD falls under.
Copd. COPD chronic obstructive pulmonary disease- a disease of terminal bronchioles with thick secretions obstructing the airway/ or loss of elasticity causing decreased air exchange at the level of alveoli. Whereas chronic air way obstruction implies physical obstruction such as stenosis, tumors, ( extrinsic or intrinsic) impeding the airflow.