Overview of Permissions by Place

Permissions are different depending on the place you assign them -- for example, in a space, blog, or social group.

System Administration
These permissions allow users administrative and moderation permissions to system-wide settings. Most of the permission levels available here provide access to the Admin Console. With the exception of the Full Access permission level, these don't provide access to content. You can't break out the bundled permissions in the administrative area (as you can with space permissions).
Spaces
These permissions allow users administrative or content moderation permissions in a space. Projects contained by a space inherit the permissions of their container space.
Blogs (global)
These permissions allow users to view, create, and comment on global blogs, such as system and personal blogs, neither of which belong, strictly speaking, to a place. This leaves out blogs in spaces, social groups, and projects, whose permissions are managed in different ways as described in Managing Blog Permissions.
Social Groups
These permissions allow users to view and create social groups. Projects contained by a group inherit the permissions of their container group.
Home Page
These permissions allow users to create and interact with content that can appear on the community's home page and in the user container, including announcements, polls, and videos.