Freezing Point:The temperature at which a liquid turns into a solid. It's like when your melted ice cream gets put back in the freezer and becomes solid again.
Phase Transition: A change from one state of matter (solid, liquid, gas) to another without changing its chemical composition. Like going from an ice cube (solid water) to water (liquid) or steam (gas).
Heat of Fusion:The amount of energy required to change one gram of substance from the solid phase to the liquid phase at its melting point.