The difference between Voltage and electric potential is just that, its a difference.  Electric potential is a measurement of the possible energy at one given point. Voltage on the other hand is referring to two points and the difference in the electric potential between those two points.  A positively charged particle that is free to move, will move from the highest potential to the lowest potential, so when we consider particles and motion it is easier to look at it in the terms of voltage instead of electric potential.

What is an Electron Volt  

  A unit of energy used for convenience in atomic systems. Specifically, it is the change in energy of an electron, or of any particle having a charge numerically equal to that of an electron, when it is moved through a difference of potential of 1 mks volt. Its value (in mks units) is obtained from the equation W = qV, where W is energy in joules, q the charge in coulombs, and V the potential difference in volts. For a potential difference of 1 volt and the electronic charge of 1.602 × 10−19 coulomb, the electronvolt is 1.602 × 10−19 joule.