Resistance:Resistance is a measure of how much a material opposes the flow of electric current through it. It depends on both the material's properties and its shape.
$Ohm's \ Law$: $Ohm's \ Law$ states that the current through a conductor between two points is directly proportional to the voltage across the two points, expressed as $V = IR$, where $V$ is voltage, $I$ is current, and $R$ is resistance.
Conductivity:Conductivity is a measure of a material's ability to conduct electric current. It is the reciprocal of resistivity.