heating vs melt

heating and melt both are nouns.

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

As nouns, melt is a hyponym of heating; that is, melt is a word with a more specific, narrower meaning than heating:

heating (noun)	melt (noun)
utility to warm a building	the process whereby heat changes something from a solid to a liquid
the process of becoming warmer; a rising temperature

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