meld vs merge

meld is a noun but merge is not a noun.

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

As verbs, meld and merge are synonyms defined as:

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

As verbs, merge is a hypernym of meld; that is, merge is a word with a broader meaning than meld:

Other hypernyms of meld include blend, coalesce, combine, commingle, conflate, flux, fuse, immix, meld, mix.

meld (noun)	merge (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

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