nightfall vs crepuscle

nightfall and crepuscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
nightfall	Yes	No	No	No
crepuscle	Yes	No	No	No

As nouns, nightfall and crepuscle are synonyms defined as:

Other synonyms of nightfall include crepuscule, dusk, evenfall, fall, gloam, gloaming, twilight.

nightfall (noun)	crepuscle (noun)
the time of day immediately following sunset	the time of day immediately following sunset