acetophenetidin vs pain pill

acetophenetidin and pain pill both are nouns.

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

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

acetophenetidin: a white crystalline compound used as an analgesic and also as an antipyretic
pain pill: a medicine used to relieve pain

Other hypernyms of acetophenetidin include analgesic, anodyne, painkiller.

acetophenetidin (noun)	pain pill (noun)
a white crystalline compound used as an analgesic and also as an antipyretic	a medicine used to relieve pain