Conductance: The reciprocal of resistance is called conductance. It is denoted by G. The unit of conductance is ohm-1 or mho or siemen (S).
G = \(\frac{1}{R}\)
Conductivity. It is a measure of ease with which the current flows through a conductor. R is defined as the reciprocal resistivity. It is denoted by σ.
σ = \(\frac{1}{p}\)
The unit of σ is mho m-1 or Sm-1.