Should you set up a group or a page? The answer depends on what kind of interaction you want, and the resources you have.
|Anyone can post||Admins can post|
|Anyone can comment||Anyone can comment|
|Posts go to top when commented on||Posts appear in chronological order|
|One admin role||Multiple levels of admin roles|
|Pinned post||Pinned post|
|Public or closed or secret||Public|
A group is best used for discussion, while a page is most useful as a static information source.