The difference between the electrode potentials of two electrodes when no current is drawn through the cell is called:
1. Cell potential.
2. Cell emf.
3. Potential difference.
4. Cell voltage.

HINT: It is the basic definition of Cell emf.
Explanation:
Cell emf -The difference between the electrode potential of two electrodes when no current is drawn through the cell is called cell emf.
 

Emf

Potential difference
It is the potential difference between two electrodes when no current is flowing in the circuit. It is the difference of the electrode potentials of the two electrodes when the cell is under operation.
It is the maximum voltage that the cell can deliver. It is always less then the maximum value of voltage which the cell can deliver.
It is responsible for the steady flow of current in the cell. It is not responsible for the steady flow of current in the cell.
 
EMF Voltage
It denotes the voltage produced inside the electric source. It is the difference potential difference between two points
External forces work in moving a charge from one pole to another pole inside a source It is the work in moving a charge from one pole to another through a wire
E = I * (R + r) V = I * R
It follows the coulomb force operation It follows a non-coulomb force operation
It measured with EMF meter It is measured with a voltmeter
It is always greater than the voltage It is always lesser than EMF