infestation vs plague

infestation and plague both are nouns.

Word	Noun	Adjective	Verb	Adverb
infestation	Yes	No	No	No
plague	Yes	No	Yes	No

As nouns, infestation and plague are synonyms defined as:

infestation (noun)	plague (noun)
a swarm of insects that attack plants	an annoyance
the state of being invaded or overrun by parasites	any large scale calamity (especially when thought to be sent by God)
	a swarm of insects that attack plants
	a serious (sometimes fatal) infection of rodents caused by Yersinia pestis and accidentally transmitted to humans by the bite of a flea that has bitten an infected animal
	any epidemic disease with a high death rate

infestation (verb)	plague (verb)
	annoy continually or chronically
	cause to suffer a blight