pettifog vs niggle

pettifog and niggle both are verbs.

Word	Noun	Adjective	Verb	Adverb
pettifog	No	No	Yes	No
niggle	No	No	Yes	No

As verbs, pettifog and niggle are synonyms defined as:

Other synonyms of pettifog include bicker, brabble, quibble, squabble.

pettifog (verb)	niggle (verb)
argue over petty things	argue over petty things
	worry unnecessarily or excessively