cunningly vs slyly

cunningly and slyly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
cunningly	No	No	No	Yes
slyly	No	No	No	Yes

As adverbs, cunningly and slyly are synonyms defined as:

Other synonyms of cunningly include artfully, craftily, foxily, knavishly, trickily.

cunningly (adverb)	slyly (adverb)
in an subtle, cunning manner	in an subtle, cunning manner
in an attractive manner