Question

Which level(s) of the federal judicial system has/have only appellate jurisdiction

Answer 1

The Courts of Appeal are the only courts that have strictly appellate jurisdiction.

Answer 2

The United States circuit courts, or, as they're also know, courts of appeals, are the intermediate appellate courts of the United States federal court system. A circuit court decides appeals from the district courts within its federal judicial circuit. Sometimes it also decides appeals from other administrative agencies or designated federal courts.