yowl vs roar

yowl and roar both are nouns.

Word	Noun	Adjective	Verb	Adverb
yowl	Yes	No	Yes	No
roar	Yes	No	Yes	No

As nouns, yowl and roar are synonyms defined as:

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

yowl (noun)	roar (noun)
a very loud utterance (like the sound of an animal)	a very loud utterance (like the sound of an animal)
	a deep prolonged loud noise
	the sound made by a lion

yowl (verb)	roar (verb)
utter shrieks, as of cats	laugh unrestrainedly and heartily
cry loudly, as of animals	make a loud noise, as of wind, water, or vehicles
	emit long loud cries
	utter words loudly and forcefully
	make a loud noise, as of animal
	act or proceed in a riotous, turbulent, or disorderly way