Cuban itch vs smallpox

Cuban itch and smallpox both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cuban itch	Yes	No	No	No
smallpox	Yes	No	No	No

As nouns, smallpox is a hypernym of Cuban itch; that is, smallpox is a word with a broader meaning than Cuban itch:

Cuban itch: a mild form of smallpox caused by a less virulent form of the virus
smallpox: a highly contagious viral disease characterized by fever and weakness and skin eruption with pustules that form scabs that slough off leaving scars

Other hypernyms of Cuban itch include variola, variola major.

Cuban itch (noun)	smallpox (noun)
a mild form of smallpox caused by a less virulent form of the virus	a highly contagious viral disease characterized by fever and weakness and skin eruption with pustules that form scabs that slough off leaving scars