What is the difference between mother and daughter CNG station?

What is the difference between mother and daughter CNG station?
Online Station:
Online stations are directly connected with the Natural Gas Pipeline. At online station, natural Gas is received at a pressure of 19 barg and then compressed upto a pressure of 250 barg with the help of a reciprocating compressor in order to enhance the on board storage capacity of vehicle. Then, it is dispensed to vehicles locally through CNG dispensers at a pressure of 200 barg. Typically a CNG Online Stations consists of following equipments:CNG CompressorCNG DispenserStorage Cascade
Mother Station:
Mother stations are similar to an online station, where it has the facility to refuel the mobile cascades in addition to the local demand of vehicles. These mobile cascades are then dispatched to other stations, which do not have the connectivity of pipeline.
Daughter Station:
Daughter stations do not have the connectivity of natural gas pipeline. At these stations, compressed natural gas (CNG) is transported through mobile cascades (bunch of cylinders mounted on trucks) at a pressure of 240-250 barg and then dispensed to vehicles through CNG dispensers. In fact, under stopped condition of CNG Compressor, a mother/online station acts as a Daughter Station and dispensed the gas from the local storage cascades.