convection vs natural action

convection and natural action both are nouns.

Word	Noun	Adjective	Verb	Adverb
convection	Yes	No	No	No
natural action	Yes	No	No	No

As nouns, natural action is a hypernym of convection; that is, natural action is a word with a broader meaning than convection:

convection: (meteorology) the vertical movement of heat or other properties by massive motion within the atmosphere
natural action: a process existing in or produced by nature (rather than by the intent of human beings)

Other hypernyms of convection include action, activity, natural process.

convection (noun)	natural action (noun)
the transfer of heat through a fluid (liquid or gas) caused by molecular motion	a process existing in or produced by nature (rather than by the intent of human beings)
(meteorology) the vertical movement of heat or other properties by massive motion within the atmosphere