In Electrical theory What is really a potential and what is the difference?

Answer 1

in simple definition:

potential is charge on an object ( or rather the electron content)
potential difference is difference in the charges of different objects in consideration.

hope it helps.

Answer 2

Potential is just that: the ability to do work. A 1.5V battery has a potential of 1.5V.

Now between the negative and positive terminals on the battery, if you use the battery in a circuit, the voltage across the terminals is the potential difference.