LibGuides sites have one additional permission: Edit All Guides. Select this if you want this Regular level user to be able to edit all guides in the system without having to add them as a Guide Editor to every guide and without having to make them an Admin level user, which would grant them access to everything in the system.
LibGuides CMS sites have a number of user permissions options:
►Edit All Guides (same as described above)
►Manage Subjects / Tags / Friendly URLs
Allows Regular users access to this item in the Admin menu, where they can create / edit / delete in each of these sections.
Allows Regular users full Admin-level-like access to the Content > Assets area. They can add / edit / delete Content Items (no matter which user "owns" them), Databases, and Icons.
Allows Regular users full Admin-level-like access to the Content > E-Reserves area. They can add / edit / delete any Courses / Items and manage all settings.
Allows Regular users full Admin-level-like access to the Discussions area (internal and public). They can add or edit / delete any discussion / post, mark answers as correct, manage tags, etc.
►Manage mSite Builder Sites
Allows Regular users access to the Content > mSite Builder area, where they can add / edit / delete mSites and their related settings/content. (Regular users don't usually have access to this area at all.)