cruelty vs brutality

cruelty and brutality both are nouns.

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

As nouns, brutality is a hyponym of cruelty; that is, brutality is a word with a more specific, narrower meaning than cruelty:

Other hyponyms of cruelty include ferociousness, savagery, viciousness, murderousness.

cruelty (noun)	brutality (noun)
a cruel act; a deliberate infliction of pain and suffering	a brutal barbarous savage act
the quality of being cruel and causing tension or annoyance	the trait of extreme cruelty
feelings of extreme heartlessness