piddling vs petty

piddling is not a noun while petty is a noun.

Word	Noun	Adjective	Verb	Adverb
piddling	No	Yes	No	No
petty	Yes	Yes	No	No

As adjectives, piddling and petty are synonyms defined as:

Other synonyms of piddling include fiddling, footling, lilliputian, little, niggling, picayune, piffling, trivial.

piddling (noun)	petty (noun)
	larceny of property having a value less than some amount (the amount varies by locale)

piddling (adjective)	petty (adjective)
(informal) small and of little importance	inferior in rank or status
	contemptibly narrow in outlook
	(informal) small and of little importance