Electric Current is defined as the amount of electric charge flowing through any cross section of conductor in unit time. It is denoted by I and its SI unit is Ampere (A).
Voltage is also known as Electric Potential Difference Or Electric Potential.
Consider a positively charged sphere. This sphere would have an electric field around it,in which it will exert attractive force for a negative charge and repulsive force for a positive charge.
Now, consider a positively charged particle just outside the electric field of the sphere. We call this position as infinity. Now, we would have to exert force and do work on the particle to bring it near to the sphere against the force of repulsion. Suppose we bring it to a point A in the electric field and leave the particle. Now, the work done by us gets stored in the particle in the form of Electric Potential Energy. As soon as we leave the particle, this potential energy changes into kinetic energy and the particle moves away from the sphere (due to repulsive force).
Now consider that we bring the same particle from point A mentioned above to point B further closer to the sphere against the force of repulsion. This particle would now gain more electric potential. The difference in electric potential at point A and Point B is called Electric Potential Difference between these two points or simply Voltage (V).
Thus, Electric Potential Difference (Voltage) can be defined as the work done to bring a unit positive charge from Point A to B against the electric force of repulsion in the electric field.