The main difference between 32- and 64-bit operating systems (usually Windows) is that one deals with information in a more efficient way. In order to use a 64-bit client of WoW, you need to have a 64-bit operating system on your computer.
This is great news for people with computers that have large amounts of RAM and hefty processors, as well as great news for general improvements to WoW's structure itself. Blizzard, which has been hinting at a 64-bit WoW client for some time now, has finally announced that such a client exists and can be downloaded for testing on the PTR. One of the most frequently asked questions around here these days is what exactly the difference is between a 32- and 64-bit client of World of Warcraft.
