unchangeability vs changelessness

unchangeability and changelessness both are nouns.

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

As nouns, unchangeability and changelessness are synonyms defined as:

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

Other synonyms of unchangeability include unchangeableness, unchangingness.

unchangeability (noun)	changelessness (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
	the property of remaining unchanged