nom de guerre vs anonym

nom de guerre and anonym both are nouns.

Word	Noun	Adjective	Verb	Adverb
nom de guerre	Yes	No	No	No
anonym	Yes	No	No	No

As nouns, nom de guerre and anonym are synonyms defined as:

nom de guerre and anonym: a fictitious name used when the person performs a particular social role

Other synonyms of nom de guerre include pseudonym.

nom de guerre (noun)	anonym (noun)
a fictitious name used when the person performs a particular social role	a fictitious name used when the person performs a particular social role