Resistance vs. conductance

Resistance

• a measure of its opposition to the flow of electric current. 
• Electrical resistance shares some conceptual parallels with the notion of mechanical friction.
• measured in ohm
• depends in large part on the material it is made of. 
• Objects made of electrical insulators like rubber tend to have very high resistance and low conductivity, while objects made of electrical conductors like metals tend to have very low resistance and high conductivity.
• formula
• R = V / I
• Resistivity
• quantifies how strongly it resists electric current
• represented by the Greek letter ρ (rho).
• SI unit of electrical resistivity is the ohm-meter (Ω⋅m)

Conductance 

• the ease with which an electric current passes.
• measured in siemens
• formula
• G =  I / V = 1 / R
• Conductivity
• quantifies how strongly it conducts electric current
• The SI unit of electrical conductivity is siemens per metre (S/m).