Grand juries are the ones who determine if you're guilty or not. Trial juries are the ones who see if there are enough evidence to go to the Grand jury.
Both typically protect someone's rights. Most of the time. Trial juries have a talk with the concerned/assumed person to see if they look like they'd do it. If so. then they'd search for evidence or peers. Then the grand jury most of the time is fair. Using evidence provided concludes the case.
