thermal barrier vs heat barrier

thermal barrier and heat barrier both are nouns.

Word	Noun	Adjective	Verb	Adverb
thermal barrier	Yes	No	No	No
heat barrier	Yes	No	No	No

As nouns, thermal barrier and heat barrier are synonyms defined as:

thermal barrier and heat barrier: a limit to high speed flight imposed by aerodynamic heating

thermal barrier (noun)	heat barrier (noun)
a limit to high speed flight imposed by aerodynamic heating	a limit to high speed flight imposed by aerodynamic heating