As nouns,
chronic obstructive pulmonary disease is a hyponym of
emphysema; that is,
chronic obstructive pulmonary disease is a
word with a more specific, narrower meaning than
emphysema:
- emphysema: an abnormal condition of the lungs marked by decreased respiratory function; associated with smoking or chronic bronchitis or old age
- chronic obstructive pulmonary disease: a nonreversible lung disease that is a combination of emphysema and chronic bronchitis; usually patients have been heavy cigarette smokers