holla vs holloa

holla and holloa both are nouns.

Word	Noun	Adjective	Verb	Adverb
holla	Yes	No	No	No
holloa	Yes	No	No	No

As nouns, holla and holloa are synonyms defined as:

Other synonyms of holla include bellow, bellowing, holler, hollering, hollo, roar, roaring, yowl.

holla (noun)	holloa (noun)
a very loud utterance (like the sound of an animal)	a very loud utterance (like the sound of an animal)