Answer :

Emf describe the force required to separate two charges at a given distance.While potential difference is simply a voltage difference between two points in a closed electrical circuit with a voltage source circuit.It can be a source of emf if it use to move charges.
Work done by the electric force on unit positive charge to move it through a distance 'l' from A to B is called potential difference between those points. It is also called as voltage. Whereas e.m.f is defined as the work done by the chemical force to move unit positive charge from negative terminal to positive terminal of the battery.