vapour vs phase change

vapour and phase change both are nouns.

Word	Noun	Adjective	Verb	Adverb
vapour	Yes	No	No	No
phase change	Yes	No	No	No

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

vapour: the process of becoming a vapor
phase change: a change from one state (solid or liquid or gas) to another without a change in chemical composition

Other hypernyms of vapour include phase transition, physical change, state change.

vapour (noun)	phase change (noun)
the process of becoming a vapor	a change from one state (solid or liquid or gas) to another without a change in chemical composition
a visible suspension in the air of particles of some substance