pig vs swine

pig and swine both are nouns.

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

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

pig (noun)	swine (noun)
domestic swine	stout-bodied short-legged omnivorous animals
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