So, I was thinking again (dangerous, I know), and I noticed that the order of the elements in Tarot and Astrology are different! This might seem minor to some, but for people who base part of their conception of the Tarot on the order of the elements (that would be me), this is shocking! The traditional elemental order in the Tarot is Fire (Origin), Water (Potential), Air (Thought), and then Earth (Realization). In Astrology, Fire (Origin) is first, followed by Earth (Realization), then Air (Thought) and Water (Potential). Water and Earth are switched in the astrological system!
After a few moments of panic, I began to rationalize this, and came to the conclusion that both orders are logical. The Tarot order makes sense because it starts off with a spark (Fire), which then gains potential (Water) and is defined then by thought (Air), which results in its manifestation in reality (Earth). An order of creation, based on the Tree of Life.
On the other hand, the astrological model is not one of creation, but of cycles. Fire begins as an initiator, providing activity to start things off, and is followed then by a manifestation on Earth. This manifestation is then observed and rationalized by Air, and after that it gains new potential through Water, which allows for another spark to ignite and carry on the cycle. This model makes sense for astrology, as there is an emhpasis on the cyclical nature of the Zodiac and similar, cyclical changes.