Do all motorhome propane tanks refill the same way?

There ARE different fittings on propane tanks but any place selling propane should have the adapters to fit. I've seen two different adapters hanging on the fill station walls. I know the tank fittings now are somewhat larger than they were years ago. Any place that sells propane should train their employees but I've repeatedly encountered clerks who tell me "this is my first time filling an RV". SMH.