unexceptionable vs unimpeachable

unexceptionable and unimpeachable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unexceptionable	No	Yes	No	No
unimpeachable	No	Yes	No	No

As adjectives, unexceptionable and unimpeachable are synonyms defined as:

unexceptionable and unimpeachable: completely acceptable; not open to exception or reproach

unexceptionable (adjective)	unimpeachable (adjective)
completely acceptable; not open to exception or reproach	completely acceptable; not open to exception or reproach
	free of guilt; not subject to blame
	beyond doubt or reproach