crepuscle vs nightfall

crepuscle and nightfall both are nouns.

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

As nouns, crepuscle and nightfall are synonyms defined as:

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

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