In cybersecurity, the main difference between a virus and a worm lies in their methods of propagation. A virus attaches itself to a host file and replicates whenever the file is executed, often requiring user action to spread. In contrast, a worm is a standalone malicious program that can self-replicate and spread autonomously across networks without user intervention. Both can cause damage, but worms tend to spread more rapidly and broadly than viruses, making them particularly dangerous in cybersecurity contexts.