As nouns the difference between multifariousness and multifarity
is that multifariousness is (uncountable) the characteristic of being multifarious while multifarity is the quality of being multifarious; multifariousness.
multifariousness
English
Noun
(es)
(uncountable) The characteristic of being multifarious.
multifarity
English
Noun
(-)
The quality of being multifarious; multifariousness.