swindle vs diddle

swindle is a noun but diddle is not a noun.

Word	Noun	Adjective	Verb	Adverb
swindle	Yes	No	Yes	No
diddle	No	No	Yes	No

As verbs, swindle and diddle are synonyms defined as:

Other synonyms of swindle include bunco, con, defraud, goldbrick, hornswoggle, mulct, nobble, rook, scam, short-change, victimize.

swindle (noun)	diddle (noun)
the act of swindling by some fraudulent scheme

swindle (verb)	diddle (verb)
deprive of by deceit	manipulate manually or in one's mind or imagination
	deprive of by deceit