jury vs petit jury

jury and petit jury both are nouns.

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

As nouns, petit jury is a hyponym of jury; that is, petit 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
petit 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, petty jury, blue ribbon jury, special jury.

jury (noun)	petit 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