Opened through Window > Show View > UML Navigator, the UML Navigator provides an alternate view of your projects in Together. You can see all the elements for your projects at a glance.
The UML Navigator is, in many ways, a scaled-down version of the UML Explorer. It is focused primarily on modeling, whereas the UML Explorer combines useful visual and functional advantages from the Together UML Navigator with the Package Explorer.
UML Explorer vs. UML Navigator:
In the Together help documents, the terms "UML Explorer" and "UML
Navigator" are sometimes used interchangeably. Menu commands that you can
access through the UML Navigator can also be accessed through the UML Explorer.