You can convert groups to linked Revit models, and you can convert linked Revit models to groups.
It is recommended that you use groups when there is significant geometrical interactivity in a model (for example, joins, inserts, or references) and where project standards need to be managed in one location. Sample scenarios where you would use groups are hotel rooms, apartments, and repeating floors.
Switching between groups and links may be useful in the following scenarios:
When you convert a group to a linked Revit model, any excluded elements are restored in the link. For more information about excluded elements, see Exclude Elements from a Group Instance.