Substances can undergo physical changes or chemical changes. what is the difference between these two kinds of changes

Physical changes are those change which just externally or physically change the state of the object. for example : water boils and evaporates ... here the state is just changing from liquid to vapour while the composition is the same.

chemical changes are those which bring about a change in the composition of a substance. for example: burning of paper changes into ash.

There are several differences between a physical and chemical change in matter or substances. A physical change in a substance doesn't change what the substance is. In a chemical change where there is a chemical reaction, a new substance is formed and energy is either given off or absorbed.