cruelty vs harshness

cruelty and harshness both are nouns.

Word	Noun	Adjective	Verb	Adverb
cruelty	Yes	No	No	No
harshness	Yes	No	No	No

As nouns, cruelty and harshness are synonyms defined as:

cruelty and harshness: the quality of being cruel and causing tension or annoyance

Other synonyms of cruelty include cruelness.

cruelty (noun)	harshness (noun)
a cruel act; a deliberate infliction of pain and suffering	the quality of being harsh or rough or grating to the senses
the quality of being cruel and causing tension or annoyance	excessive sternness
feelings of extreme heartlessness	the roughness of a substance that causes abrasions
	the quality of being cruel and causing tension or annoyance