What is the difference in lapboard and clapboard?

If there are no differences, then there cannot be a difference of anything, so there is no difference of different and difference.

A spoken language difference is simply when you and another person (say, a patient) do not speak the same language. A cultural difference is where something that is accepted in your culture is not...

To specifically answer the question, there is no such thing as 'voltage difference' because, by definition, 'voltage' means 'potential difference' -not 'potential'! You can compare 'potential' with...

voltage is a deference in potential energy between a baseline, of say "ground" and what has been induced by some sort of a generator into a conductor.

the attittude is the last difference