This is a rough schematic of signal transmission performed using differential signaling over a balanced line. The sender produces two copies of the original signal with equal magnitude but opposite polarity. A differential amplifier at the receiving end produces the difference between the two signals leading to a signal identical to the original but with twice the amplitude.
During transmission there is noise added to the signal, but do to the impedance balanced line, the noise is induced equally in both conductors and the differential amplifier rejects it entirely.

Based on DiffSignaling.png by Linear77
Own work
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