What is the difference between a trial jury and a grand jury?

A trial jury, also known as a petit jury, is composed of six to 12 members and decides whether a defendant injured a plaintiff in a civil case or committed a crime as charged in a criminal case. Defendants have the right to appear, testify and call witnesses on their behalf before a trial jury, whose proceedings are generally public. Trial jury deliberations, which are in private, produce a verdict in favor of the plaintiff or defendant in a civil case, or guilty or not guilty in a criminal case.

A grand jury is composed of 16 to 23 members and determines whether there is probable cause to believe that an individual has committed a crime and should stand trial. Grand jury proceedings are not public, and defendants and their attorneys do not have a right to appear before the grand jury. The grand jury will decide whether to hand down an indictment, or formally accuse, the defendant.