merge vs meld

merge is not a noun while meld is a noun.

Word	Noun	Adjective	Verb	Adverb
merge	No	No	Yes	No
meld	Yes	No	Yes	No

As verbs, merge and meld are synonyms defined as:

Other synonyms of merge include blend, coalesce, combine, commingle, conflate, flux, fuse, immix, mix.

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

merge (noun)	meld (noun)
	a form of rummy using two decks of cards and four jokers; jokers and deuces are wild; the object is to form groups of the same rank

merge (verb)	meld (verb)
become one	mix together different elements
mix together different elements	lose its distinct outline or shape; blend gradually
join or combine	announce for a score; of cards in a card game