piffling vs petty

piffling is not a noun while petty is a noun.

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

As adjectives, piffling and petty are synonyms defined as:

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

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

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