Lenovo tab 4 plus available storage

My bundled file manager for lenovo tab 4 10" plus says "Main Storage 16G", "Personal Space 8.72G". When I use file managers from the playstore they only see this 8.72G as available. Is this storage all I really have available on this new tablet ? Or is the other space somehow available and I need to delete/modify the "personal space" structure ??