Melting is the change from solid to liquid.
In a solid, particles stay around fixed positions. Add energy and they move more.
At the melting point, the solid structure can no longer stay fully organised and the material becomes liquid.
An ice cube, wax near a flame and molten metal all show the same kind of change.
A pure substance can have a sharp melting temperature, while mixtures often melt over a range. Real materials can therefore soften gradually.
A useful way to understand this phenomenon is to separate the driving force from the visible result. Temperature, pressure, concentration, surface area and the nature of the materials can each change the rate or the final state. In real systems, several of these factors often act at the same time.
That is why the same phenomenon can look different in a laboratory, in the kitchen or outdoors. The underlying chemistry or physics stays the same, but the conditions change the balance.
Real examples often add one more layer: geometry, impurities, coatings, humidity, flow or manufacturing history can alter what you observe even when the main mechanism is unchanged.
That is why two objects made from broadly similar materials can behave differently. The useful question is not only “what is it made of?” but also “how is it built, under what conditions, and for which function?”