melting vs phase transition

melting and phase transition both are nouns.

Word	Noun	Adjective	Verb	Adverb
melting	Yes	Yes	No	No
phase transition	Yes	No	No	No

As nouns, phase transition is a hypernym of melting; that is, phase transition is a word with a broader meaning than melting:

melting: the process whereby heat changes something from a solid to a liquid
phase transition: a change from one state (solid or liquid or gas) to another without a change in chemical composition

Other hypernyms of melting include heating, warming, phase change, physical change, state change.

melting (noun)	phase transition (noun)
the process whereby heat changes something from a solid to a liquid	a change from one state (solid or liquid or gas) to another without a change in chemical composition

melting (adjective)	phase transition (adjective)
becoming liquid