prolificacy vs fruitfulness

prolificacy and fruitfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
prolificacy	Yes	No	No	No
fruitfulness	Yes	No	No	No

As nouns, fruitfulness is a hypernym of prolificacy; that is, fruitfulness is a word with a broader meaning than prolificacy:

prolificacy: the property of producing abundantly and sustaining vigorous and luxuriant growth
fruitfulness: the quality of something that causes or assists healthy growth

Other hypernyms of prolificacy include fecundity.

prolificacy (noun)	fruitfulness (noun)
the property of producing abundantly and sustaining vigorous and luxuriant growth	the quality of something that causes or assists healthy growth
	the intellectual productivity of a creative imagination