bellowing vs vociferation

bellowing and vociferation both are nouns.

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

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

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

bellowing (noun)	vociferation (noun)
a very loud utterance (like the sound of an animal)	a loud utterance; often in protest or opposition