It was proposed to me recently that the Light Side of the Force seems to be more Yin in nature, while the Dark Side is more Yang. While one side might appear more passive and internal, and the other more active and external, Yin and Yang are fundamental Principles of the Force, and there is no movement of the Force itself without each of them intertwined in some way.
The fundamental difference between the Way that the Sith use the Force versus the Jedi actually has very little to do with “dark” and “light,” those are simply linguistic metaphors which are unfortunately misused more often than not. The difference is actually more about the Karma involved, and the nature of the dynamics of Energy that unfold when one acts out of Anger or Hate, versus when one acts out of Love, Truth, or Honor.
In short, Anger is like a poorly controlled fire: it burns you, can spread chaotically, and in terms of transformation, it requires suffering on all sides. Truth on the other hand is like a laser: it shines exactly where it is needed, maintains self-integrity, and can also be painful in transformation, but only for a moment before a healing naturally happens.
The pain and self-destructive properties of Anger and Fear are addictive, as they seem to offer short term gratification while slowly rotting away the integrity of the Self over time. For those who have taken the path of the Dark Side, one of the only allures is tricking others into doing so in order to gain more power and watch others suffer, simply to relieve their own struggle for a time.
When aligned with the True Way of the Force, one understands these principles of creation and destruction. Learning to balance the desires of the ego and temper the need for short term satisfaction, one aligns more with the flow of Sacred Purpose, which gently and surely enables and empowers the Self to improve on All Levels.