This is because you are showing different features.
Your first attachment shows the Grid Spacing of the 3D Custom Workshop Power Tool. As you can see in my first attachment, this is a feature that belongs to this particular Power Tool (Power Tools have their own settings). In the User Guide, you will find this menu in the page 340 that belongs to the 3D Custom Workshop section (that starts at page 335)
Your second attachment shows the Grid Settings of the main program. As you can see in my second attachment, this is a feature that is part of the Design options of the main program. In the User Guide, you will find this menu in the page 59 that explains how to set the program's grid and snaps.
Hope this helps