pair creation vs natural action

pair creation and natural action both are nouns.

Word	Noun	Adjective	Verb	Adverb
pair creation	Yes	No	No	No
natural action	Yes	No	No	No

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

pair creation: the transformation of a gamma-ray photon into an electron and a positron when the photon passes close to an atomic nucleus
natural action: a process existing in or produced by nature (rather than by the intent of human beings)

Other hypernyms of pair creation include action, activity, natural process.

pair creation (noun)	natural action (noun)
the transformation of a gamma-ray photon into an electron and a positron when the photon passes close to an atomic nucleus	a process existing in or produced by nature (rather than by the intent of human beings)