Isn’t salt just salt? What are the differences? +

All salts are different. They differ in their source (mined salt like the Himalayan, versus sea salt like Hawaiian Black Lava Salt). Some offer advantages for cooking, like Sel Gris. Others, for their appearance or the shape of their crystals (Fleur de Sel for example), and are more suited for sprinkling on top of prepared food as a finishing salt.