describe the difference between a physical property and a chemical property

A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance. Physical properties include color, density, hardness, and melting and boiling points. A chemical property describes the ability of a substance to undergo a specific chemical change. 

Physical properties without needing to make any chemical changes to a substance (i.e. no bonds needs to be made or broken, and the chemical composition of the substance is not changed).

So things like colour, melting point, boiling point, density, hardness and so on are all physical properties.

Chemical properties can only be measured and observed by making changes to the substance on an atomic/molecular scale by forming or breaking chemical bonds. So something like heat of combustion can only be measured by combusting the substance. Enthalpy of formation can only be measured by forming a (new) substance. These are chemical properties.