salt pork vs fatback

salt pork and fatback both are nouns.

Word	Noun	Adjective	Verb	Adverb
salt pork	Yes	No	No	No
fatback	Yes	No	No	No

As nouns, fatback is a hyponym of salt pork; that is, fatback is a word with a more specific, narrower meaning than salt pork:

salt pork: fat from the back and sides and belly of a hog carcass cured with salt
fatback: salt pork from the back of a hog carcass

Other hyponyms of salt pork include sowbelly.

salt pork (noun)	fatback (noun)
fat from the back and sides and belly of a hog carcass cured with salt	salt pork from the back of a hog carcass