In terms of design BALANCED cables have 3 wires ( 1 Signal (+), 2 Signal (-) and 3 Ground), while UNBALANCED cables have only two (Signal and Ground).
The addition of the 3rd wire in a balanced cable is exactly what makes noise-cancellation possible. That’s because when audio enters a balanced cable both the (+) and (-) wires receive identical versions of the signal, the only difference is, polarity of the (-) wire is INVERTED.
As the two signals travel along the cable, BOTH wires gather noise, the same way unbalanced cables do, however before re-combining them at the opposite end of the cable, the polarity of the negative wire is flipped BACK, to once again match the positive signal.
With the noise patterns now on OPPOSITE polarities, they cancel each other out, leaving the original signal noise-free.