Potential means the Potential to move charge. Also know as "Voltage", Potential is like pressure in a fluid system. Potential difference is like a difference in pressure. Also, a difference in Voltage. In a circuit, there will be potential at one point [V1] and potential at another point [V2]. The potential between those two points is the potential difference: Vdelta = V1 - V2.
It's that simple.
