morphine vs pain pill

morphine and pain pill both are nouns.

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

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

morphine: an alkaloid narcotic drug extracted from opium; a powerful, habit-forming narcotic used to relieve pain
pain pill: a medicine used to relieve pain

Other hypernyms of morphine include analgesic, anodyne, painkiller, opiate.

morphine (noun)	pain pill (noun)
an alkaloid narcotic drug extracted from opium; a powerful, habit-forming narcotic used to relieve pain	a medicine used to relieve pain