coldheartedness vs heartlessness

coldheartedness and heartlessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
coldheartedness	Yes	No	No	No
heartlessness	Yes	No	No	No

As nouns, coldheartedness and heartlessness are synonyms defined as:

coldheartedness and heartlessness: an absence of concern for the welfare of others

Other synonyms of coldheartedness include hardheartedness.

coldheartedness (noun)	heartlessness (noun)
an absence of concern for the welfare of others	an absence of concern for the welfare of others