A civil case is an action between parties seeking an impartial settlement of a dispute. The "plaintiff" sues and brings the case to court usually asking for money damages to compensate the plaintiff for certain losses. These are called "compensatory damages." Sometimes the plaintiff may ask for damages in addition to the compensatory damages, in order to punish the defendant and to prevent the defendant from doing the same act again. These are called "punitive damages." The "defendant" is the party being sued.
A criminal case is an action brought by the state against a person or corporation charged with violating the law. In criminal cases, the state is the prosecutor, while the defendant is the person charged with committing the crime. In most criminal cases on which you may be asked to serve, the crime with which the defendant is charged will be a "felony." A felony is a crime punishable by at least one year and one day in the penitentiary and may also include a fine. Sometimes, a jury will be demanded by a defendant in a misdemeanor case. A misdemeanor is a crime punishable by up to one year in the county jail or a fine up to $2,000 or both.