Are different offices of same car rental chain (Sixt) in Germany really different?

I have arranged to rent a car from Sixt in Munich, Germany. It was two months ago and i don't remember if the car rental near the Central Station (Haubtbahnhof) did not have the car i wanted, if the price was different or if their reviews were bad. As it is i rented from a location at some distance from the station.

However i think we are better of getting a car at the station, as we arrive by train. I have sent Sixt a mail to see if they will change the reservation and how much if anything they will charge.

But I'm curious, is Sixt just Sixt everywhere? Or are those distinct German car rental agencies with their own cars, that just operate under a Sixt umbrella? Can i expect a big difference in service or price from one location to the next?