antitussive vs codeine

antitussive and codeine both are nouns.

Word	Noun	Adjective	Verb	Adverb
antitussive	Yes	No	No	No
codeine	Yes	No	No	No

As nouns, codeine is a hyponym of antitussive; that is, codeine is a word with a more specific, narrower meaning than antitussive:

antitussive: any medicine used to suppress or relieve coughing
codeine: derivative of opium; used as an antitussive (to relieve coughing) and an analgesic (to relieve pain)

antitussive (noun)	codeine (noun)
any medicine used to suppress or relieve coughing	derivative of opium; used as an antitussive (to relieve coughing) and an analgesic (to relieve pain)