How does coupling and bypass capacitors differ?

It is a difference in function. The same capacitor can be used for both functions. Coupling capacitors are used to allow high frequency signals to pass through while blocking low frequency signals, especially DC. read more

A bypass capacitor is to conduct the frequency to ground, typically on a power supply to minimize noise or ripple, or can be across the emitter/ source resistor to ground to increase gain. In RF circuits there are often two bypass capacitors in parallel. read more

An alternative name is bypass capacitor as it is used to bypass the power supply or other high impedance component of a circuit Decoupling capacitors are typically in parallel with an IC or circuit. In analog circuits, a coupling capacitor is used to join two circuits such that simply an AC signal from the first circuit is able to pass throughout the next circuit while the DC is blocked. read more

Coupling capacitors. While decoupling capacitors are connected in parallel to the signal path and are used to filter out the AC component, coupling capacitors, on the other hand, are connected in series to the signal path and are used to filter out the DC component of a signal. They are used in both analog and digital circuit applications. read more