The Planar Elements require the existence and balance of each other and the Core Elements to exist. Should any of these elements falter or become imbalanced, the other elements would follow. This balance is held and controlled by the Elemental Planes (or Elemental Courts, in some namings), where the elemental Vaazarai (or djinn) battle each other. A positive side-effect of their battles is that they maintain the natural elements on not only their plane, but on Tariel as well. As such their never-ending wars are essential for the existence of our world. In simpler terms, the Core Elements are required to maintain the natural balance of the world.
The Planar Elements consist of Air, Water, Fire and Earth, and were the main elements used by the Elemental Lords during their time as the masters of Tariel, long before the arrival of the Creators. It is these four elements that engraved themselves upon the world and made it dependent on their existence. Together these four Planar Elements act as the roots of which the world holds onto. The Dependent Elements cannot exist without the Planar Elements' presence.
The Core Elements consist of Ethereal, Mana, Astral and Nature. These are powers that have existed long before the other elements, and feed the lesser elements. Godly beings such as the Creators used the Core Elements to breathe new life into Tariel during the Creator Times.
The Core Elements represent the powers of
the world and the universe that maintain the Elemental Balance, and
they are energies and powers that are not necessarily noticed by the
naked eye. If magic (or mana) was to dissipate completely from the
world, the other elements (save for Astral, which is the greater source
of magic) would suffer and die. Unlike the other elements, the Core
Elements do not require their aid to exist. It is still unknown where
the Core Elements draw their power from (possibly from the gods
themselves), yet as far as anyone has learned thus far, it is believed
that the Core Elements simply do not require any sources, and are
limitless on their own.
However, an exception to this rule is Nature, which does require some assistance from not only the other Core Elements, but the lesser elements as well. In return Nature trades any excess energies to further feed the lesser elements. This is a dependency that has grown over the many eons of its existence. Nature is also a calmer element; meaning it is far more susceptible to be controlled by a mage or druid.
Mana, in its simpler terms, is an element which exists everywhere. All living beings harbour mana within them, though some individuals are born with more than average. It is usually these individuals that become mages and such, as their mana-rich blood allows them to maintain better control over not only the elements, but all energies pertaining to magic.
Ethereal is the element which controls the spiritual aspects of the world and universe. It is the element which allows shamans and druids to communicate with the natural and ancestral spirits of the world.
Astral is the most powerful element, as all other elements of the world and universe were born from it over the duration of millions of years. While its true source is unknown, it is believed that Astral gave birth to the first Creators. It is the power which controls the energies of the entire universe, far beyond the confines of the Tariel and its planes.