In the mobile app, all 44,000 campgrounds will be available to view offline. You can verify this through your user settings in the "Me" tab. This is separate from the "Map Downloads"
Campground Database is a comprehensive list of all those listed on The Dyrt. Periodically refresh this list to hav access to all the newest adds, deletions and updates to campgrounds.
Maps is a downloaded version of the map/maps you want to view while offline.