What's the difference between Potential Difference and Electromotive Force

Although both are measured in volts, there is a subtle difference in their respective definition. Electromotive Force is the transfer of chemical energy in a battery (multiple single cells) into electrical energy per unit charge. Potential Difference is the transfer of electrical energy to other forms per unit charge, like kinetic in a motor or to hear in a heating element.
Both can be worked out numerically by computing V=W/Q