unify vs weld

unify is not a noun while weld is a noun.

Word	Noun	Adjective	Verb	Adverb
unify	No	No	Yes	No
weld	Yes	No	Yes	No

As verbs, weld is a hyponym of unify; that is, weld is a word with a more specific, narrower meaning than unify:

Other hyponyms of unify include consolidate, consubstantiate.

unify (noun)	weld (noun)
	a metal joint formed by softening with heat and fusing or hammering together
	European mignonette cultivated as a source of yellow dye; naturalized in North America

unify (verb)	weld (verb)
become one	unite closely or intimately
join or combine	join together by heating
to bring or combine together or with something else
act in concert or unite in a common purpose or belief
bring together for a common purpose or action or ideology or in a shared situation