efficaciousness vs effectivity

efficaciousness and effectivity both are nouns.

Word	Noun	Adjective	Verb	Adverb
efficaciousness	Yes	No	No	No
effectivity	Yes	No	No	No

As nouns, effectivity is a hypernym of efficaciousness; that is, effectivity is a word with a broader meaning than efficaciousness:

efficaciousness: capacity or power to produce a desired effect
effectivity: power to be effective; the quality of being able to bring about an effect

Other hypernyms of efficaciousness include effectiveness, effectuality, effectualness.

efficaciousness (noun)	effectivity (noun)
capacity or power to produce a desired effect	power to be effective; the quality of being able to bring about an effect