scream vs yell

scream and yell both are nouns.

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

As nouns, yell is a hypernym of scream; that is, yell is a word with a broader meaning than scream:

Other hypernyms of scream include call, cry, outcry, shout, vociferation.

As verbs, scream and yell are synonyms defined as:

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

As verbs, scream and yell are synonyms defined as:

scream (noun)	yell (noun)
sharp piercing cry	a loud utterance; often in protest or opposition
a joke that seems extremely funny	a loud utterance of emotion (especially when inarticulate)
a high-pitched noise resembling a human cry

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