irruption vs outbreak

irruption and outbreak both are nouns.

Word	Noun	Adjective	Verb	Adverb
irruption	Yes	No	No	No
outbreak	Yes	No	No	No

As nouns, irruption and outbreak are synonyms defined as:

irruption and outbreak: a sudden violent spontaneous occurrence (usually of some undesirable condition)

Other synonyms of irruption include eruption.

irruption (noun)	outbreak (noun)
a sudden violent entrance; a bursting in	a sudden violent spontaneous occurrence (usually of some undesirable condition)
a sudden violent spontaneous occurrence (usually of some undesirable condition)
a sudden sharp increase in the relative numbers of a population