outbreak vs natural event

outbreak and natural event both are nouns.

Word	Noun	Adjective	Verb	Adverb
outbreak	Yes	No	No	No
natural event	Yes	No	No	No

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

outbreak: a sudden violent spontaneous occurrence (usually of some undesirable condition)
natural event: an event that happens

Other hypernyms of outbreak include happening, occurrence, occurrent.

outbreak (noun)	natural event (noun)
a sudden violent spontaneous occurrence (usually of some undesirable condition)	an event that happens