A trebuchet is a type of catapult that uses a rotating arm with a sling attached to the tip to launch a projectile. It was a common powerful siege engine until the advent of gunpowder. The design of a trebuchet allows it to launch projectiles of greater weights and further distances than that of a traditional catapult.
Replica counterweight trebuchets at Château de Castelnaud
Counterweight trebuchet used in a siege from the Jami' al-tawarikh, c. 1306-18
The onager was a torsion powered weapon used in Europe from the 4th until the 6th century AD.
Wheeled whirlwind traction trebuchet from the Wujing Zongyao
A catapult is a ballistic device used to launch a projectile a great distance without the aid of gunpowder or other propellants – particularly various types of ancient and medieval siege engines. A catapult uses the sudden release of stored potential energy to propel its payload. Most convert tension or torsion energy that was more slowly and manually built up within the device before release, via springs, bows, twisted rope, elastic, or any of numerous other materials and mechanisms.
Ancient mechanical artillery: Catapults (standing), the chain drive of Polybolos (bottom center), Gastraphetes (on wall)
Engraving illustrating a Roman catapult design, 1581
Roman "catapult-nest" in the Trajan's Dacian Wars
Replica of a Petraria Arcatinus