What is CURRENT and what is VOLTAGE ?

VOLTAGE 
 

Every atom has its own complement of electrons. In a conductor, some of those electrons can jump from atom to atom. But electrons don't move from atom to atom without a reason. When electrons are flowing there is always an electrical force pushing them along. We refer to this force as "Voltage". 

Voltage, also called electromotive force, is the potential difference in "charge" between two points in an electrical field. In other words, voltage is the "energy per unit charge”. 

We define voltage as the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage. It is measured in volts, which, technically, is the potential energy difference between two points that will impart one joule of energy per coulomb of charge that passes through it (don’t panic if this makes no sense, all will be explained). The unit “volt” is named after the Italian physicist Alessandro Volta who invented what is considered the first chemical battery. Voltage is represented in equations and schematics by the letter “V”.

CURRENT

Current is the rate at which electric charge flows past a point in a circuit. In other words, current is the rate of flow of electric charge.

This picture illustrates a single cell pocket flashlight. The 1.5 Volt cell is pushing the electrons through the bulb and the wire. Without this push, the electrons would be happy to remain stationary. In this case, chemical action within the battery causes the push. When the battery gets old, its chemical reaction slows down and its internal push gets weaker and weaker. (That's why the bulb gets dim.) http://www.reprise.com/host/electricity/voltage.asp

Who Does the Work?

Current, not Voltage, does the work in electrical circuits. The flow of water through a turbine is what makes the turbine spin. The flow of current through an electrical circuit is what lights the bulb, heats the stove, runs the motor, etc. Routing and controlling the flow of current is the goal of every electrical circuit. 


A detailed comparison between current and voltage as on Diffen.com:

	Current	Voltage
Definition	Current is the rate at which electric charge flows past a point in a circuit. In other words, current is the rate of flow of electric charge.	Voltage, also called electromotive force, is the potential difference in charge between two points in an electrical field. In other words, voltage is the "energy per unit charge”.
Symbol	I	V
Unit	A or amps or ampere	V or volts or voltage
SI Unit	1 ampere =1 coulomb/second.	1 volt = 1 joule/coulomb.
Measuring Instrument	Ammeter	Voltmeter
Relationship	Current is the effect (voltage being the cause). Current cannot flow without Voltage.	Voltage is the cause and current is its effect. Voltage can exist without current.
Field created	A magnetic field	An electrostatic field
In series connection	Current is the same through all components connected in series.	Voltage gets distributed over components connected in series.
In a parallel connection	Current gets distributed over components connected in parallel.	Voltages are the same across all components connected in parallel.