Awareness of Ignorance
We know libertarians are fundamentally different from republicans, democrats, socialists, communists, etc. and we all have ideas about the nature of the difference. Here's another; what makes libertarians different is awareness of their own ignorance.
For example: the right price of water. The stronger statists will say that water should be free but regulated so that it is not overused or wasted. Moderates may favor a sliding price scale to encourage industry, with subsidies so the poor will have good free water to drink. Communists might support decisions by committees of citizens to decide water policy or select representatives to decide for everyone. Conservatives would favor control by local government, and so on. Each believes they know the right price or they know how to find the right price for water.
A libertarian will tell you the market will decide. Market prices are whatever buyers and sellers agree on. Libertarians not only don't know the right price for water, they believe there's no such thing as the right price for water. Wherever water sells someone else can sell at a different price and be just as right.
What makes us different is that we know we don't know. Think about this for a moment. We could say the democrats don't know what's best but the republicans say that. Saying we ourselves don't know what's best makes us completely unique. We don't know how to govern the world, we believe that it isn't possible to know how to govern the world. Human behavior is so complex compared to human imagination that it is the height of folly to imagine that you can make good decisions for people you've never met. The best you can do is let them make their own decisions, and how do you do that? By not interfering with them.
Even our strongest opponents can agree with this description of libertarianism. Statists agree that libertarians don't know how to run the world. It can be disarming when talking with them to take this approach.