illegitimately vs illicitly

illegitimately and illicitly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
illegitimately	No	No	No	Yes
illicitly	No	No	No	Yes

As adverbs, illegitimately and illicitly are synonyms defined as:

illegitimately and illicitly: in a manner disapproved or not allowed by custom

illegitimately (adverb)	illicitly (adverb)
of biological parents not married to each other	in a manner disapproved or not allowed by custom
in a manner disapproved or not allowed by custom	in an illegal manner