unevenness vs variability

unevenness and variability both are nouns.

Word	Noun	Adjective	Verb	Adverb
unevenness	Yes	No	No	No
variability	Yes	No	No	No

As nouns, unevenness and variability are synonyms defined as:

unevenness and variability: the quality of being uneven and lacking uniformity

unevenness (noun)	variability (noun)
the quality of being uneven and lacking uniformity	the quality of being subject to variation
the quality of being unbalanced	the quality of being uneven and lacking uniformity