Difference between conficker a/b variant

[Saaz]

I have been always wondering what is the need and different variants of same virus and worms? The latest has been the most deadliest worm, the conficker. What is the difference between conficker a/b variant? Can anyone explain? Thanks!

[Spyrus]

A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes or computers on the network and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or devour files on a targeted computer. Many worms that have been created are only designed to spread, and don't attempt to alter the systems they pass through. However, as the Morris worm and Mydoom showed, the network traffic and other unintended effects can often cause major disruption. A "payload" is code designed to do more than spread the worm - it might delete files on a host system. As worms are detected and new antivirus database signature is created, they are evolved with the same name but different variant or versions so that they cannot be stopped by antivirus programs. Hope you understand now, what is the use of versions....

[Saaz]

Yeah, Thanks for the information. I understood whats the use of updating a virus by the hackers. Also can you tell me the basic difference between Conficker A and B variants? Thanks again..!

[Snake08]

Here is an image stating the difference between the two variants of conficker.