illicitly vs illegitimately

illicitly and illegitimately both are adverbs.

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

As adverbs, illicitly and illegitimately are synonyms defined as:

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

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