certainly vs sure enough

certainly and sure enough both are adverbs.

Word	Noun	Adjective	Verb	Adverb
certainly	No	No	No	Yes
sure enough	No	No	No	Yes

As adverbs, certainly and sure enough are synonyms defined as:

certainly and sure enough: definitely or positively (`sure' is sometimes used informally for `surely')

Other synonyms of certainly include for certain, for sure, sure, sure as shooting, surely.

certainly (adverb)	sure enough (adverb)
definitely or positively (`sure' is sometimes used informally for `surely')	as supposed or expected
	definitely or positively (`sure' is sometimes used informally for `surely')