unrelenting vs relentless

unrelenting and relentless both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unrelenting	No	Yes	No	No
relentless	No	Yes	No	No

As adjectives, unrelenting and relentless are synonyms defined as:

Other synonyms of unrelenting include persistent.

As adjectives, unrelenting and relentless are synonyms defined as:

unrelenting and relentless: not to be placated or appeased or moved by entreaty

Other synonyms of unrelenting include grim, inexorable, stern, unappeasable, unforgiving.

unrelenting (adjective)	relentless (adjective)
never-ceasing	never-ceasing
not to be placated or appeased or moved by entreaty	not to be placated or appeased or moved by entreaty
punishingly harsh