merge vs fuse

merge is not a noun while fuse is a noun.

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

As verbs, merge and fuse are synonyms defined as:

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

merge (noun)	fuse (noun)
	any igniter that is used to initiate the burning of a propellant
	an electrical device that can interrupt the flow of electrical current when it is overloaded

merge (verb)	fuse (verb)
become one	mix together different elements
mix together different elements	make liquid or plastic by heating
join or combine	become plastic or fluid or liquefied from heat
	equip with a fuse; provide with a fuse