inexorableness vs relentlessness

inexorableness and relentlessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
inexorableness	Yes	No	No	No
relentlessness	Yes	No	No	No

As nouns, inexorableness and relentlessness are synonyms defined as:

inexorableness and relentlessness: mercilessness characterized by an unwillingness to relent or let up

Other synonyms of inexorableness include inexorability.

inexorableness (noun)	relentlessness (noun)
mercilessness characterized by an unwillingness to relent or let up	mercilessness characterized by an unwillingness to relent or let up