Single-Ended vs Differential [hlp]

Hello Everyone;
What is the relation between a "single-ended" quantity and its "differential" counterpart?

Usually the value of the differential signal depends on the difference in the amplitude between the two signals and the phase difference between them.

The single-ended or differential configuration is chosed by the designer, depending on application.
Single-ended - ground is the return path for the signal.
Differential - ground is not used as a reference, so the ground coupled noise is eliminated.
Differential - because the signal subtraction, any common mode signal (same amplitude and phase with reference to gropund on both inputs) is eliminated - egg parasitic signals present on long balanced cables.

To convert between single ended <-> differential, u can use a transformer or coupler.