unforgiving vs implacable

unforgiving and implacable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unforgiving	No	Yes	No	No
implacable	No	Yes	No	No

unforgiving (adjective)	implacable (adjective)
unwilling or unable to forgive or show mercy	incapable of being placated
not to be placated or appeased or moved by entreaty