# Difference between current and voltage waves with the transverse electromagnetic waves on a transmission line

In a transmission line consisting of 2 parallel wires, one can show that the voltage and current exist as a wave propagating along the wire.

When calculating, for example, the reflection coefficient due to an unmatched load, one uses the waveforms $$V_0e^{i(\omega t - kz)}$$ $$I_0e^{i(\omega t - kz)}$$ to derive the result. However, why do we not use $$E_0e^{i(\omega t - kz)}$$ $$H_0e^{i(\omega t - kz)}$$ (representing the propagating E and H fields) for this derivation?

Essentially what I am unsure of is the difference between the propagating voltage and current waves with the propagating EM waves in a transmission line. Are they one of the same thing?

Any help will be much appreciated.