Why the potential difference in parallel circuit is same?

Suppose R1 and R2 are the resistances connenected in series. The R1 and R2 are connected in sries across a voltage V. The resitance R2 is not connected direcly to the source it is connected to the resistance R1. So it recieves its voltage from R1 after a drop. Whereas in a parallel circuit the both R1 and R2 are connected to across the same voltage directly and R2 . In as series connected resistors (or components) the same current flows through all the resistors, but voltage drops from resistor to resitor and the sum of the voltage across each resistor(or component) is the total voltage . Whereas, in a parallel connected resistors, the  voltage across each resistor (or component) is same whereas the sum of the current through the components is the total current of the system