initiative vs commencement

initiative and commencement both are nouns.

Word	Noun	Adjective	Verb	Adverb
initiative	Yes	Yes	No	No
commencement	Yes	No	No	No

As nouns, commencement is a hypernym of initiative; that is, commencement is a word with a broader meaning than initiative:

Other hypernyms of initiative include beginning, start.

initiative (noun)	commencement (noun)
the first of a series of actions	the act of starting something
readiness to embark on bold new ventures	an academic exercise in which diplomas are conferred
	the time at which something is supposed to begin

initiative (adjective)	commencement (adjective)
serving to set in motion