inexorability vs relentlessness

inexorability and relentlessness both are nouns.

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

As nouns, inexorability and relentlessness are synonyms defined as:

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

Other synonyms of inexorability include inexorableness.

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