A parlour as we understand it being a place where you can walk in, check out the girls, take a pick and have sex, is a brothel.
But a place can be a brothel, in legal terms, but not be a parlour.
Most Chinese places only have one girl, usually you call in advance, although it is possible to just walk up, there is no beauty parade as usually there is only one girl, who rotates every week. The law labels a parlour as being a place where sex is sold by more than one person (that's not an exact description but hope it will do) but they don't have to be there at the same time.
Hope that helps.