halloo vs vociferation

halloo and vociferation both are nouns.

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

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

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

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

halloo (verb)	vociferation (verb)
shout `halloo', as when greeting someone or attracting attention
urge on with shouts