first step vs opening move

first step and opening move both are nouns.

Word	Noun	Adjective	Verb	Adverb
first step	Yes	No	No	No
opening move	Yes	No	No	No

As nouns, first step and opening move are synonyms defined as:

Other synonyms of first step include initiative, opening.

first step (noun)	opening move (noun)
the first of a series of actions	the first of a series of actions