unchangeability vs unchangingness

unchangeability and unchangingness both are nouns.

Word	Noun	Adjective	Verb	Adverb
unchangeability	Yes	No	No	No
unchangingness	Yes	No	No	No

As nouns, unchangeability and unchangingness are synonyms defined as:

unchangeability and unchangingness: the quality of being unchangeable; having a marked tendency to remain unchanged

Other synonyms of unchangeability include changelessness, unchangeableness.

unchangeability (noun)	unchangingness (noun)
the quality of being unchangeable; having a marked tendency to remain unchanged	the quality of being unchangeable; having a marked tendency to remain unchanged