WEE Technology Company Limited - WEE are Capacitors Specialist

What is the difference between 100V capacitor and 200V capacitor (used in frequency divider)?
There should be no difference. The capacitance in the divider is basically about capacity
The same specifications, high voltage withstand, large volume, good insulation performance.
When using, if the conditions permit, choose the capacitor with high withstand voltage as far as possible.

What's the difference between 50V and 200V Loudspeaker Capacitor ?
They are different in withstand voltage. In theory, 100V capacitor is higher than 50V power supply. The general use allowance is 80-90%
Therefore, the power supply with 100V capacitor may be more than 80V
Using 50V may be about 40-45V

WMH - Pure Aluminum Foil Audio Capacitor 

WMH Al Foil Film Met PP 6.8uF 100V +/-3% Axial RoHS
WMH Al Foil Film Met PP 6.8uF 200V +/-3% Axial RoHS