melt vs merge

melt is a noun but merge is not a noun.

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

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

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

melt (noun)	merge (noun)
the process whereby heat changes something from a solid to a liquid

melt (verb)	merge (verb)
become or cause to become soft or liquid	become one
reduce or cause to be reduced from a solid to a liquid state, usually by heating	mix together different elements
lose its distinct outline or shape; blend gradually	join or combine
become more relaxed, easygoing, or genial
become less clearly visible or distinguishable; disappear gradually or seemingly
become less intense and fade away gradually