waul vs howl

waul is not a noun while howl is a noun.

Word	Noun	Adjective	Verb	Adverb
waul	No	No	Yes	No
howl	Yes	No	Yes	No

As verbs, howl is a hypernym of waul; that is, howl is a word with a broader meaning than waul:

Other hypernyms of waul include roar, ululate, wail, yaup, yawl.

waul (noun)	howl (noun)
	a long loud emotional utterance
	a loud sustained noise resembling the cry of a hound
	the long plaintive cry of a hound or a wolf

waul (verb)	howl (verb)
make high-pitched, whiney noises	laugh unrestrainedly and heartily
	make a loud noise, as of wind, water, or vehicles
	emit long loud cries
	cry loudly, as of animals