Simplify the following text for a Grade 14 native English-speaking person.
Original: In the water flow analogy sometimes used to explain electric circuits by comparing them to water-filled pipes , voltage difference is likened to water pressure differenceâ `` the difference determines how quickly the electrons will travel through the circuit .
Simplified: In the hydraulic analogy sometimes used to explain electric circuits by comparing them to water-filled pipes , voltage is likened to water pressure - it determines how fast the electrons will travel through the circuit .