devilishly vs insanely

devilishly and insanely both are adverbs.

Word	Noun	Adjective	Verb	Adverb
devilishly	No	No	No	Yes
insanely	No	No	No	Yes

As adverbs, devilishly and insanely are synonyms defined as:

Other synonyms of devilishly include deadly, deucedly, madly.

devilishly (adverb)	insanely (adverb)
in a playfully devilish manner	in an insane manner
(used as intensives) excessively	(used as intensives) excessively
as a devil; in an evil manner