Heat is a form of energy; temperature shows how hot a thing is. In other words, heat refers to the quantity of energy present in a substance, while temperature refers to its intensity, i.e. the degree of hotness.
For example, a glass of boiling water has the same temperature as a large can full of boiling water. Even though the temperature of water in the two vessels is the same, the glass does not possess as much heat as the can.
Subtraction or addition of heat is necessary to lower or to raise the temperature of a substance. Besides, differences in temperature determine the direction of heat flow from one body to another.
As we all know, heat moves from a hotter body to a colder body. Therefore temperature has been defined as the property which determines whether heat will flow out of or into an object when in contact with another object.
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According to the molecular theory of matter, heat represents the total energy of motion of the molecules in a substance. The fact is that a substance is composed of a number of molecules which are always in a state of constant motion, and there are frequent collisions between them.
Because of their dashing against one another their kinetic energy is converted into heat energy. Therefore heat is taken to be representing the total energy of the molecular motion in a substance.
Temperature, on the other hand, measures the average kinetic energy of motion of the molecules. In other words, temperature is the measurement of available or sensible heat energy in a system.