You use the check boxes in the lower left corner of the main window to filter the comparison results:
Select Hide Identical Objects (the default) to list only elements and documents that are different in the two panes. Clear this check box to see the complete database design— elements and documents that are identical and elements and documents that are different.
Select Smart Filter to hide or filter information that is of no practical interest when comparing the database designs.
Select Hide Unique Notes to hide notes that exist in only one of the databases you are comparing.