opening night vs curtain raising

opening night and curtain raising both are nouns.

Word	Noun	Adjective	Verb	Adverb
opening night	Yes	No	No	No
curtain raising	Yes	No	No	No

As nouns, opening night and curtain raising are synonyms defined as:

opening night and curtain raising: the first performance (as of a theatrical production)

Other synonyms of opening night include opening.

opening night (noun)	curtain raising (noun)
the first performance (as of a theatrical production)	the first performance (as of a theatrical production)