indistinguishable vs indistinguishability

indistinguishable is not a noun while indistinguishability is a noun.

Word	Noun	Adjective	Verb	Adverb
indistinguishable	No	Yes	No	No
indistinguishability	Yes	No	No	No

indistinguishable (noun)	indistinguishability (noun)
	exact sameness

indistinguishable (adjective)	indistinguishability (adjective)
not capable of being distinguished or differentiated
exactly alike; incapable of being perceived as different