squeal vs howl

squeal and howl both are nouns.

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

As nouns, howl is a hypernym of squeal; that is, howl is a word with a broader meaning than squeal:

squeal (noun)	howl (noun)
a high-pitched howl	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

squeal (verb)	howl (verb)
confess to a punishable or reprehensible deed, usually under pressure	laugh unrestrainedly and heartily
utter a high-pitched cry, characteristic of pigs	make a loud noise, as of wind, water, or vehicles
	emit long loud cries
	cry loudly, as of animals