Heat vs Temperature — What's the Difference?
Heat
Heat is thermal energy transferred between objects because of a temperature difference. It is energy on the move — once the transfer stops, there is no 'heat' left, only internal energy.
Unit: joule (J)
Example: Holding a hot cup, heat flows from the cup into your cooler hands. A sparkler is extremely hot but transfers little heat because it holds almost no thermal energy.
Temperature
Temperature measures the average kinetic energy of the particles in a substance. It tells you how hot something is and which way heat will flow, but not how much energy is stored.
Unit: kelvin (K)
Example: A swimming pool at 25 °C has far more total thermal energy than a boiling cup of tea at 100 °C — the pool is cooler but enormously larger.
Key differences
| Aspect | Heat | Temperature |
|---|---|---|
| What it is | Energy in transit | Average kinetic energy per particle |
| Unit | Joule (J) | Kelvin (K) or °C |
| Stored? | Exists only while flowing | A property a body has at every instant |
| Direction matters | Heat flows from hot to cold | Temperature has no direction |
| Phase change | Ice melting at 0 °C absorbs heat with no temperature change | Stays constant while heat flows in |
Touching metal feels 'colder' than wood at the same temperature because metal conducts heat away from your hand faster — your skin senses heat flow, not temperature. And 'heating something up' can mean raising its temperature or adding heat at constant temperature (like melting ice).