The Original and the PRO motors fit the same silicone parts.
The Ella's motor has its own silicone parts and won't fit the Original and PRO pump parts.

ALL ELLA MOTORS ARE NOW PINK! These pink motors can replace the white model 

If you have the Original Pump and want to upgrade to the PRO, you can simply buy the PRO motor as opposed to buying the whole PRO Pump.

Please note this type of breast pump part does not come with a charging cable.

The Original Pump requires a Micro USB cable 
The PRO & Ella require a USB-C Cable