How so? What are the differences?
Different version number of the software and blur, this one is signed by Motorola and the other one is not. There is a list somewhere of the differences, but being that this one is signed, you can manually install it without being rooted.
So if you are a stock, non-root user who just wants GB, you just have to copy the update.zip file to your SD card and boot into the stock recovery screen and apply the update.
You only have to do the other steps with the other files if you want it rooted.