pox vs varicella

pox and varicella both are nouns.

Word	Noun	Adjective	Verb	Adverb
pox	Yes	No	No	No
varicella	Yes	No	No	No

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

pox: a contagious disease characterized by purulent skin eruptions that may leave pock marks
varicella: an acute contagious disease caused by herpes varicella zoster virus; causes a rash of vesicles on the face and body

Other hyponyms of pox include smallpox, variola, variola major, chickenpox, cowpox, vaccinia.

pox (noun)	varicella (noun)
a contagious disease characterized by purulent skin eruptions that may leave pock marks	an acute contagious disease caused by herpes varicella zoster virus; causes a rash of vesicles on the face and body
a common venereal disease caused by the treponema pallidum spirochete; symptoms change through progressive stages; can be congenital (transmitted through the placenta)