recrudescence vs irruption

recrudescence and irruption both are nouns.

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

As nouns, irruption is a hypernym of recrudescence; that is, irruption is a word with a broader meaning than recrudescence:

recrudescence: a return of something after a period of abatement
irruption: a sudden violent spontaneous occurrence (usually of some undesirable condition)

Other hypernyms of recrudescence include eruption, outbreak.

recrudescence (noun)	irruption (noun)
a return of something after a period of abatement	a sudden violent entrance; a bursting in
	a sudden violent spontaneous occurrence (usually of some undesirable condition)
	a sudden sharp increase in the relative numbers of a population