In the Star Wars Universe, the difference between the light side and dark side is...a gray area.
Essentially, if you are using the Force out of anger, lust, greed, vengeance, or fear, you likely channel the dark side.
If you are using the Force to defend you are using the light side.
There are very few techniques which are unambiguously light or dark.
The ability to stimulate cellular regeneration ('Force Heal') is generally considered light, but a malicious individual could use it to restore health to a torture victim, for instance, to prepare them for more.
The only truly unique powers to either side are, I believe, Force Choke and Force Lightning.
These are unambiguous mainly because they use the Force explicitly to kill.
No other power seen uses the force for that purpose, and it can even be seen as mildly damaging to the Force itself to do so (since the Force is generated by life, using it to bring death is abominable).
For the most part, Force powers are tools, neither good nor bad on their own.
Their USER is light or dark.
scifi.stackexchange.com/users/656/Jeff
The Force is different things to different cultures:
The Old Jedi Council considered any Force use that requires emotion to be of the dark side, and the light side to be that which requires knowledge and control with the absence of emotion.
Several cultures believe that the Force is magic and that any attempt to use it is evil.
The Sith believe the Force is nothing more than a tool to be used for the wielder's ends.
In New Jedi Order and beyond there has been a lot of experimentation with techniques that would have been banned under the Jedi Council.
The current Jedi Order seems to have taken an approach akin to the Shao-Lin seeking Discipline and Control over Emotion, allowing for slips and mistakes and having the belief that the fallen can be redeemed if brought back early enough.
It is not uncommon to see the different Jedi straying towards the dark side (including Leia) only to be brought back by the masters.
scifi.stackexchange.com/users/2131/Chad
Drawing a line between the light and dark side is a very subjective decision.
For example, we know that Mace Windu used a fighting technique he called Vaapad, which channeled raw ferocity from the opponent back at them.
This is described as stepping over the line into tapping into the dark side of the force, but is an acceptable Jedi technique (although dangerous).
So light versus dark is really a personal if not organizational designation determined by subjective ethics.
scifi.stackexchange.com/users/541/Adam
The Force is ambiguous (do Midichlorians really pick sides?).
It is the desire of the person using the Force that can be considered "Light" or "Dark".
The reason why some powers are associated with Sith (or Dark) vs Jedi (or Light) is likely because some are easier to enact using one method over another (raw emotion versus mental discipline).
scifi.stackexchange.com/users/1234/Xantec
A gun is neither good nor evil, nor is any 'thing' (and with this I would include a "power" as a thing) .
It is all about HOW it is used and perhaps more importantly WHY it is used.
Several examples have been provided already about how a power can be used for good or evil, I would challenge anyone to suggest a power of the Force that could NOT be used "for good".
Leaving us with " the difference " being in the heart or mind of the person using the Force, and in 'the Force' itself.
scifi.stackexchange.com/users/2169/Cos Callis
I hate bring feminism down on the crew here, but the overwhelming gist of the Force seems to me to be very Old Testament.
I mean, where are the chicks in positions of power?
Princess Leia never gets to fly in battle, and Padme just wrecks everything.
Oh, yeah,
and she dies in childbirth yawn .
I guess the force is just to keep me in my place.
There's some hope though.
Since the rights of black men generally precede the rights of women, there is a Black man jedi.
A.
The dark side gets laid.
scifi.stackexchange.com/users/2188/Ele Munjeli
The difference between the light and the dark side of the force is life itself.
The force may appear neutral but since the dark side is usually used to kill or do harm to other beings while the light side respects and protects life as much as possible, then those who used the light side in the long run will probably be in a stronger and better position to triumph because of the more numerous allies they are able to make and instruct, over time compared to the Sith Lords who only live to dominate and do harm to others, Sith included.
They are always fighting each other for survival or power.
Why do you think the Jedi are able to establish an order and high council while the Sith regularly stepped on one another and have to abide by the famous "rule of two" of Darth Banes?
That means, while a Jedi, no matter how strong he can become is no threat to another one, and are allowed to freely multiply themselves by the thousands and become a very strong force, the Sith can only be allowed to be two of them at the same time:
One Sith lord and his apprentice.
Thus, no matter how strong the dark side, on any given day, a dark lord, no matter how powerful will have to confront thousands of Jedi at the same time.
Then, because of their strength in numbers, the Jedi can only be defeated by the Sith lords only through extraordinary means of treachery, surprise or treason.
The servant of the light side would win 9 battles out of ten.
Ultimately, eventhough the dark side of the force may appear more appealing and more powerfull on a personal point of view, it is nonetheless self destructive and doomed to be defeated by too many enemies(the Jedi).
scifi.stackexchange.com/users/22923/user22923
We know that Dark side is linked to emotion like fear and anger, but the interesting point here is the between line the two side of the force.  As an example, what make Mind tricks a "acceptable" force power for a Jedi? How could you hurt someone, like Obi-Wan does in the Mos Eisley Cantina when he slashed a alien's arm off with his lightsaber, and still be a Jedi?
What's the difference between the Light side and the Dark side of the Force?
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<star-wars><powers><good-against-evil><morality>
scifi.stackexchange.com/questions/4085
scifi.stackexchange.com/users/45/DavRob60
In the Star Wars Universe, the difference between the light side and dark side is a gray area, subjective and ambiguous.  Essentially, if you are using the Force out of anger, lust, greed, vengeance, or fear, you likely channel the dark side.   If you are using the Force to defend you are using the light side.  The USER of the force may be is light or dark and the desire of the person may be light or dark. In the Star Wars universe the difference between light and dark forces is a grey area. It is considered that the User is light or dark rather than the force. Moreover, where to draw the line between light and dark is very subjective.
Certain forces are considered "dark" forces and others "light" but this is a grey area in the Star Wars universe. It is the User that is "light" or "dark" not the force. The between light and dark is very subjective.