stage name vs nom de guerre

stage name and nom de guerre both are nouns.

Word	Noun	Adjective	Verb	Adverb
stage name	Yes	No	No	No
nom de guerre	Yes	No	No	No

As nouns, nom de guerre is a hypernym of stage name; that is, nom de guerre is a word with a broader meaning than stage name:

stage name: the pseudonym of an actor
nom de guerre: a fictitious name used when the person performs a particular social role

Other hypernyms of stage name include anonym, pseudonym.

stage name (noun)	nom de guerre (noun)
the pseudonym of an actor	a fictitious name used when the person performs a particular social role