Question

define potential difference.

Answer 1

potential: usually potential means capacity to do something or existing in possibility. but in physics.
    Potential is work done by the unit positive charge to move from infinity to specific point. 
    e.g
       $V = - \int\limits^\infty_ {r}E dr$
now potential difference: change in work done per unit charge  from point  A to point B. in a simple way, a difference of potential between two points is known as potential difference. 

Answer 2

$\huge\bf\purple{Potential\:\: difference→}$

Potential difference between the two points is the amount of work done in moving a unit positive charge from one point to another.

$\large\bf\pink{Potential\:difference=Work \:done/Charge}$

$\large\bf\pink{V=W/Q}$