immediacy vs rapidity

immediacy and rapidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
immediacy	Yes	No	No	No
rapidity	Yes	No	No	No

As nouns, rapidity is a hypernym of immediacy; that is, rapidity is a word with a broader meaning than immediacy:

Other hypernyms of immediacy include celerity, quickness, rapidness, speediness.

immediacy (noun)	rapidity (noun)
the quickness of action or occurrence	a rate that is rapid
lack of an intervening or mediating agency
immediate intuitive awareness