productivity vs productiveness

productivity and productiveness both are nouns.

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

As nouns, productivity and productiveness are synonyms defined as:

productivity and productiveness: the quality of being productive or having the power to produce

productivity (noun)	productiveness (noun)
the quality of being productive or having the power to produce	the quality of being productive or having the power to produce
(economics) the ratio of the quantity and quality of units produced to the labor per unit of time