variability vs waviness

variability and waviness both are nouns.

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

As nouns, waviness is a hyponym of variability; that is, waviness is a word with a more specific, narrower meaning than variability:

Other hyponyms of variability include rockiness, ruggedness, jaggedness, patchiness.

variability (noun)	waviness (noun)
the quality of being subject to variation	(of hair) a tendency to curl
the quality of being uneven and lacking uniformity	unevenness produced by waves or wrinkles