If a substance forms crystals when it solidifies, its MELTING POINT AND FREEZING POINTS ARE THE SAME.
The melting point of a solid substance refers to the temperature at which that substance will melt to become a liquid while the freezing point of that substance is the temperature at which that substance will turn into a solid when cooled. Pure, crystalline solids have specific melting and freezing points. For crystalline solids, the melting point of the solid form is the same as the freezing point of the liquid form of the same substance.