halloo vs shout

halloo and shout both are nouns.

Word	Noun	Adjective	Verb	Adverb
halloo	Yes	No	Yes	No
shout	Yes	No	Yes	No

As nouns, shout is a hypernym of halloo; that is, shout is a word with a broader meaning than halloo:

Other hypernyms of halloo include call, cry, outcry, vociferation, yell.

As verbs, shout is a hypernym of halloo; that is, shout is a word with a broader meaning than halloo:

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

halloo (noun)	shout (noun)
a shout to attract attention	a loud utterance; often in protest or opposition

halloo (verb)	shout (verb)
shout `halloo', as when greeting someone or attracting attention	utter in a loud voice; talk in a loud voice (usually denoting characteristic manner of speaking)
urge on with shouts	utter a sudden loud cry
	utter aloud; often with surprise, horror, or joy
	use foul or abusive language towards