leather vs welt

leather and welt both are nouns.

Word	Noun	Adjective	Verb	Adverb
leather	Yes	No	Yes	No
welt	Yes	No	Yes	No

As verbs, welt is a hypernym of leather; that is, welt is a word with a broader meaning than leather:

Other hypernyms of leather include flog, lash, lather, slash, strap, trounce, whip.

leather (noun)	welt (noun)
an animal skin made smooth and flexible by removing the hair and then tanning	a raised or strengthened seam
	a raised mark on the skin (as produced by the blow of a whip); characteristic of many allergic reactions

leather (verb)	welt (verb)
whip with a leather strap	put a welt on
	beat severely with a whip or rod