soft-soap vs blarney

soft-soap is not a noun while blarney is a noun.

Word	Noun	Adjective	Verb	Adverb
soft-soap	No	No	Yes	No
blarney	Yes	No	Yes	No

As verbs, blarney is a hypernym of soft-soap; that is, blarney is a word with a broader meaning than soft-soap:

Other hypernyms of soft-soap include cajole, coax, inveigle, palaver, sweet-talk, wheedle.

soft-soap (noun)	blarney (noun)
	flattery designed to gain favor

soft-soap (verb)	blarney (verb)
use flattering talk on somebody	influence or urge by gentle urging, caressing, or flattering
persuade someone through flattery