underhanded vs sneaky

underhanded and sneaky both are adjectives.

Word	Noun	Adjective	Verb	Adverb
underhanded	No	Yes	No	No
sneaky	No	Yes	No	No

As adjectives, underhanded and sneaky are synonyms defined as:

Other synonyms of underhanded include underhand.

underhanded (adjective)	sneaky (adjective)
with hand brought forward and up from below shoulder level	marked by quiet and caution and secrecy; taking pains to avoid being observed
marked by deception	marked by deception