variola major vs smallpox virus

variola major and smallpox virus both are nouns.

Word	Noun	Adjective	Verb	Adverb
variola major	Yes	No	No	No
smallpox virus	Yes	No	No	No

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

variola major: a type of smallpox virus that has a fatality rate of up to 25 percent
smallpox virus: the virus that causes smallpox in humans; can be used as a bioweapon

Other hypernyms of variola major include variola virus.

variola major (noun)	smallpox virus (noun)
a type of smallpox virus that has a fatality rate of up to 25 percent	the virus that causes smallpox in humans; can be used as a bioweapon
a highly contagious viral disease characterized by fever and weakness and skin eruption with pustules that form scabs that slough off leaving scars