weft vs yarn

weft and yarn both are nouns.

Word	Noun	Adjective	Verb	Adverb
weft	Yes	No	No	No
yarn	Yes	No	Yes	No

As nouns, yarn is a hypernym of weft; that is, yarn is a word with a broader meaning than weft:

weft: the yarn woven across the warp yarn in weaving
yarn: a fine cord of twisted fibers (of cotton or silk or wool or nylon etc.) used in sewing and weaving

Other hypernyms of weft include thread.

weft (noun)	yarn (noun)
the yarn woven across the warp yarn in weaving	a fine cord of twisted fibers (of cotton or silk or wool or nylon etc.) used in sewing and weaving
	the act of giving an account describing incidents or a course of events

weft (verb)	yarn (verb)
	tell or spin a yarn