how can we explain the difference between the resistivity and the resistance of the conductor?
The resistance of a conductor is the ratio of potential difference across its ends to the srength of current flowing through it.
Resistance means the obstruction to the flow of electrons through it.
Resistivity is defined as the resistance offered by a cube of the material of side 1 m when the current flows perpendicular to the opposite faces of the cube. it depends on the nature of the amterial of the conductor.