likely vs in all likelihood

likely is an adjective but in all likelihood is not an adjective.

Word	Noun	Adjective	Verb	Adverb
likely	No	Yes	No	Yes
in all likelihood	No	No	No	Yes

As adverbs, likely and in all likelihood are synonyms defined as:

likely and in all likelihood: with considerable certainty; without much doubt

Other synonyms of likely include belike, in all probability, probably.

likely (adjective)	in all likelihood (adjective)
has a good chance of being the case or of coming about
within the realm of credibility
expected to become or be; in prospect

likely (adverb)	in all likelihood (adverb)
with considerable certainty; without much doubt	with considerable certainty; without much doubt