narcolepsy vs hypersomnia

narcolepsy and hypersomnia both are nouns.

Word	Noun	Adjective	Verb	Adverb
narcolepsy	Yes	No	No	No
hypersomnia	Yes	No	No	No

As nouns, hypersomnia is a hypernym of narcolepsy; that is, hypersomnia is a word with a broader meaning than narcolepsy:

narcolepsy: a sleep disorder characterized by sudden and uncontrollable episodes of deep sleep
hypersomnia: an inability to stay awake

narcolepsy (noun)	hypersomnia (noun)
a sleep disorder characterized by sudden and uncontrollable episodes of deep sleep	an inability to stay awake