animal skin vs leather

animal skin and leather both are nouns.

Word	Noun	Adjective	Verb	Adverb
animal skin	Yes	No	No	No
leather	Yes	No	Yes	No

As nouns, leather is a hyponym of animal skin; that is, leather is a word with a more specific, narrower meaning than animal skin:

animal skin: the outer covering of an animal
leather: an animal skin made smooth and flexible by removing the hair and then tanning

Other hyponyms of animal skin include lambskin, parchment, sheepskin, fell, hide, fur, pelt.

animal skin (noun)	leather (noun)
the outer covering of an animal	an animal skin made smooth and flexible by removing the hair and then tanning

animal skin (verb)	leather (verb)
	whip with a leather strap