productivity vs fruitfulness

productivity and fruitfulness both are nouns.

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

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

productivity: the quality of being productive or having the power to produce
fruitfulness: the quality of something that causes or assists healthy growth

Other hypernyms of productivity include fecundity.

productivity (noun)	fruitfulness (noun)
the quality of being productive or having the power to produce	the quality of something that causes or assists healthy growth
(economics) the ratio of the quantity and quality of units produced to the labor per unit of time	the intellectual productivity of a creative imagination