variola major vs variola virus

variola major and variola virus both are nouns.

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

As nouns, variola virus is a hypernym of variola major; that is, variola 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
variola virus: the virus that causes smallpox in humans; can be used as a bioweapon

Other hypernyms of variola major include smallpox virus.

variola major (noun)	variola 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