litterbug vs pig

litterbug and pig both are nouns.

Word	Noun	Adjective	Verb	Adverb
litterbug	Yes	No	No	No
pig	Yes	No	Yes	No

As nouns, pig is a hypernym of litterbug; that is, pig is a word with a broader meaning than litterbug:

Other hypernyms of litterbug include slob, sloven, slovenly person.

litterbug (noun)	pig (noun)
a person who litters public places with refuse	domestic swine
	a crude block of metal (lead or iron) poured from a smelting furnace
	mold consisting of a bed of sand in which pig iron is cast
	a person regarded as greedy and pig-like
	uncomplimentary terms for a policeman
	a coarse obnoxious person