As nouns the difference between plumpiness and clumpiness
is that plumpiness is the state or quality of being plumpy while clumpiness is (uncountable) the condition of being clumpy.
plumpiness
English
Noun
(-)
The state or quality of being plumpy.
clumpiness
English
Noun
(uncountable) The condition of being clumpy
(countable) A clump