Windows 8 arranges the application in their own groups. If you want you can arrange the group as expected and even rename the groups.
You can create your own groups just by dragging an app's tile to an empty space on the Start screen it'll create own group.
To rename the group as shown in below image click at the small (looks like minus) button in the bottom right corner of the start screen.
Now click on the name group and name the application group you want.