Why is it so?

How much water is going to flow from a higher to a lower level? What'll be the rate of water flow? This depends upon the difference in height of water at two different levels. Potential is analogous concept. Instead of water flow we have charge flow i.e. electric current. and the potential difference is nothing but a similar quantitiy to measure "the difference in level or potential".

Regards,

Team,

TopperLearning.