thawing vs phase transition

thawing and phase transition both are nouns.

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

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

thawing: 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 thawing include heating, warming, phase change, physical change, state change.

thawing (noun)	phase transition (noun)
warm weather following a freeze; snow and ice melt	a change from one state (solid or liquid or gas) to another without a change in chemical composition
the process whereby heat changes something from a solid to a liquid