curtain raiser vs opening move

curtain raiser and opening move both are nouns.

Word	Noun	Adjective	Verb	Adverb
curtain raiser	Yes	No	No	No
opening move	Yes	No	No	No

As nouns, opening move is a hypernym of curtain raiser; that is, opening move is a word with a broader meaning than curtain raiser:

Other hypernyms of curtain raiser include first step, initiative, opening.

curtain raiser (noun)	opening move (noun)
any preliminary activity	the first of a series of actions
a short play presented before the main play