Output Groups
Output groups are user-configured collections of outputs that you want to control together. For example, the dimmer for a row of floor lights, or the opacity or an effect parameter for all the slices of a VJ composition.
They can be configured by going to Settings > Output Groups,
and can be given any name you like.
There are no restrictions on what type of outputs can be linked to which output groups (including linking outputs of different types to the same output group), but each output can only be linked to one output group at a time.
Connecting outputs to groups can be done from their respective settings pages, see:
Note: There is no technical limit to the number of output groups you can create, but your license may have some restrictions, and adding too many output groups may make the Spell Casting interface harder to operate.
Segments
Segments are subdivisions of output groups that allow for more granular control over specific portions of your outputs. When assigning outputs to segments in their respective settings pages, you can specify which segment it should belong to.
Segments then become usable in the Casting interface, allowing you to control specific segments of your output groups independently.
Learn more about segments and their configuration on the Segments documentation page.