jury vs petty jury

jury and petty jury both are nouns.

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

As nouns, petty jury is a hyponym of jury; that is, petty jury is a word with a more specific, narrower meaning than jury:

jury: a body of citizens sworn to give a true verdict according to the evidence presented in a court of law
petty jury: a jury of 12 to determine the facts and decide the issue in civil or criminal proceedings

Other hyponyms of jury include grand jury, hung jury, petit jury, blue ribbon jury, special jury.

jury (noun)	petty jury (noun)
a body of citizens sworn to give a true verdict according to the evidence presented in a court of law	a jury of 12 to determine the facts and decide the issue in civil or criminal proceedings
a committee appointed to judge a competition