pullulate vs sprout

pullulate is not a noun while sprout is a noun.

Word	Noun	Adjective	Verb	Adverb
pullulate	No	No	Yes	No
sprout	Yes	No	Yes	No

As verbs, pullulate and sprout are synonyms defined as:

Other synonyms of pullulate include bourgeon, burgeon forth, germinate, shoot, spud.

pullulate (noun)	sprout (noun)
	a newly grown bud (especially from a germinating seed)
	any new growth of a plant such as a new branch or a bud

pullulate (verb)	sprout (verb)
breed freely and abundantly	put forth and grow sprouts or shoots
produce buds, branches, or germinate	produce buds, branches, or germinate
become abundant; increase rapidly
move in large numbers
be teeming, be abuzz