Though I personally don't follow this, figured it'd help a few people out.
The Seraphim (Serap-means to burn)
Are the closest beings to God. The bible describes them as having 6 wings each and they blaze with fiery light.
The Prophet Isaiah saw them in the temple and heard them sing 'Kadosh, Kadosh, Kadosh' which means 'Holy, Holy, Holy' In the Christian Church its sung in Latin as 'Sanctus, Sanctus, Sanctus'
The Archangels
Take charge of the hidden structures of Creation. They are the organisers and planners. They are the architects of the universe, sorting our the plans, working our where the joints and pillars should be placed and organising the fixtures and fittings. Each are in charge of their own particular area dealing with different aspects of Creation. Each has a special quality, which can help human beings to develop. For example, Archangel Michael can help us develop courage, while Archangel Raphael (healer) helps us to develop empathy.
The Angels
There are many Angels and help to brinhg about the finer things in life. They are always present - even if we dont notice them. Another of their tasks is to help us to relate to each other; they bring about emotional balance, harmony and love into our lives.
Nature Spirits
In this part of the Celestial are the faeries, elves and other elementals. They maintain the visible fabric of our planet, caring for every blade of grass, every flower and every creature, great or small. They care for our world and we do/should act like stewards helping to protect and maintain the Kingdom of Earth.
The Cherubim
They over-arch all the four realms. They are the mighty Cherubim. We see them as plump babies with wings, infact that is the total opposite of what they really are. The prophet Ezekiel saw them as Fierce creatures, shining like burnished bronze, with four faces that relate to the elements; a lion (Leo/Fire), a man (Aquarius/Air), an Eagle (an old representation for Scorpio/Water) and an ox (taurus/Earth).
They have enormous wings that spread over all four aspects of Creation, protecting and holding Creation throughout time.
Seraphim - Fire: passionate intent - beginning the process
Archangels - Air: developing the idea - maintaining the intent
Angels - Water: nurturing Creating - cooling and forming
Nature Spirits - Earth: activating form - manifestation
Also the Greeks talked about a fifth element, called Quinta Essentia (the fifth essence) or Anima Mundi (the spirits of the World). This element is like glue, holding everything together, much like the cherubim.