Worm vs a Trojan Horse -- differences?

From: xz (jasonshohet_at_gmail.com)
Date: 05/26/05 

Date: 26 May 2005 12:20:15 -0700

I know this much:
A Trojan Horse is a DDOS attack made by maliciously changing some
executable program -- like a MS Word T. Horse that infects PC w/ virus
that sends other PC's requests.
A Worm is a virus program that destroys data or utilize tramendous
network bandwidth.

My question is this - If a Trojan Horse is a DDOS attack, well a DDOS
attack also utilizes network bandwidth. So is a Trojan Horse a variety
of 'Worm', if a Worm can be loosely termed to mean any virus that sends
other PC's requests on the network?

Thanks for any clarifications!
Jason Shohet