variability vs variable

variability and variable both are nouns.

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

variability (noun)	variable (noun)
the quality of being subject to variation	a quantity that can assume any of a set of values
the quality of being uneven and lacking uniformity	a symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity
	something that is likely to vary; something that is subject to variation
	a star that varies noticeably in brightness

variability (adjective)	variable (adjective)
	liable to or capable of change
	(used of a device) designed so that a property (as e.g. light) can be varied
	marked by diversity or difference