When describing malware, what is a difference between a virus and a worm?

The difference between the two is that a virus can replicate itself by attaching to another file or program and becoming part of that program and it spreads from one computer to another leaving infections whereas a worm ca replicate itself independently. Worms are standalone software and do not require a host program or human being help to propagate, it enters a computer through a vulnerability in the system and takes advantage of file-transport or information travel.