promptitude vs rapidity

promptitude and rapidity both are nouns.

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

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

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

promptitude (noun)	rapidity (noun)
the characteristic of doing things without delay	a rate that is rapid