www.alphadictionary.com

Found this recently. How does it differ from a catapult?

Good thing I looked as I would have said something completely wrong. Here and here are Wahoo! pages with images that show the difference.

A catapult is a general term for devices to fling projectiles without explosives. A trebuchet is a specific type of catapult that generally (although not always) employs a counterweight for such purposes.

Excellent way to put it into words. Thanks. You don't by any chance know what the one that was like a giant crossbow was called, do you?

That would probably be a ballista, or possibly the more personal precursor to the crossbow, the scorpio.

http://en.wikipedia.org/wiki/Ballista

I'm not clear if you would class a ballista as a catapult - I probably would just about.

Thanks, Iain. That's the one I was thinking of.