Use these options to set what happens when you select Edit > Ungroup. See also Group objects together.
Ungroup objects under one of the following:
Puts all objects under their lowest common parent in the hierarchy. If there is none, then it puts the objects as the world level.
Puts all objects at world level (at the top-level of the hierarchy).
When on, Maya preserves the transformation information of the group. If off, the ungrouped objects lose their grouped transformation attributes, therefore changing their position when ungrouped.