first step vs beginning

first step and beginning both are nouns.

Word	Noun	Adjective	Verb	Adverb
first step	Yes	No	No	No
beginning	Yes	Yes	No	No

As nouns, beginning is a hypernym of first step; that is, beginning is a word with a broader meaning than first step:

Other hypernyms of first step include commencement, start.

first step (noun)	beginning (noun)
the first of a series of actions	the act of starting something
	the first part or section of something
	the event consisting of the start of something
	the place where something begins, where it springs into being
	the time at which something is supposed to begin

first step (adjective)	beginning (adjective)
	serving to begin