howl vs scream

howl and scream both are nouns.

Word	Noun	Adjective	Verb	Adverb
howl	Yes	No	Yes	No
scream	Yes	No	Yes	No

As verbs, scream is a hypernym of howl; that is, scream is a word with a broader meaning than howl:

Other hypernyms of howl include call, cry, holler, hollo, shout, shout out, squall, yell.

howl (noun)	scream (noun)
a long loud emotional utterance	sharp piercing cry
a loud sustained noise resembling the cry of a hound	a joke that seems extremely funny
the long plaintive cry of a hound or a wolf	a high-pitched noise resembling a human cry

howl (verb)	scream (verb)
laugh unrestrainedly and heartily	utter a sudden loud cry
make a loud noise, as of wind, water, or vehicles	utter or declare in a very loud voice
emit long loud cries	make a loud, piercing sound
cry loudly, as of animals