smallpox virus vs poxvirus

smallpox virus and poxvirus both are nouns.

Word	Noun	Adjective	Verb	Adverb
smallpox virus	Yes	No	No	No
poxvirus	Yes	No	No	No

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

smallpox virus: the virus that causes smallpox in humans; can be used as a bioweapon
poxvirus: any of a group of viruses that can cause pox diseases in vertebrates

smallpox virus (noun)	poxvirus (noun)
the virus that causes smallpox in humans; can be used as a bioweapon	any of a group of viruses that can cause pox diseases in vertebrates