propoxyphene vs pain pill

propoxyphene and pain pill both are nouns.

Word	Noun	Adjective	Verb	Adverb
propoxyphene	Yes	No	No	No
pain pill	Yes	No	No	No

As nouns, pain pill is a hypernym of propoxyphene; that is, pain pill is a word with a broader meaning than propoxyphene:

propoxyphene: a mildly narcotic analgesic drug (trade name Darvon) related to methadone but less addictive
pain pill: a medicine used to relieve pain

Other hypernyms of propoxyphene include analgesic, anodyne, painkiller.

propoxyphene (noun)	pain pill (noun)
a mildly narcotic analgesic drug (trade name Darvon) related to methadone but less addictive	a medicine used to relieve pain