ululate vs scream

ululate is not a noun while scream is a noun.

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

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

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

ululate (noun)	scream (noun)
	sharp piercing cry
	a joke that seems extremely funny
	a high-pitched noise resembling a human cry

ululate (verb)	scream (verb)
emit long loud cries	utter a sudden loud cry
	utter or declare in a very loud voice
	make a loud, piercing sound