scream vs shout out

scream is a noun but shout out is not a noun.

Word	Noun	Adjective	Verb	Adverb
scream	Yes	No	Yes	No
shout out	No	No	Yes	No

As verbs, scream and shout out are synonyms defined as:

Other synonyms of scream include call, cry, holler, hollo, shout, squall, yell.

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

scream (verb)	shout out (verb)
utter a sudden loud cry	utter a sudden loud cry
utter or declare in a very loud voice	utter in a very loud voice
make a loud, piercing sound