relentlessness vs inexorability

relentlessness and inexorability both are nouns.

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

As nouns, relentlessness and inexorability are synonyms defined as:

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

Other synonyms of relentlessness include inexorableness.

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