What is the difference between a beauty salon and a beauty parlour?

Beauty salons are more formal high-end beauty businesses where you will get more customized service from a beauty professional. A beauty salon may have full-time employees that actually work for the beauty salon as opposed to renting a booth at the salon and being an independent business owner.  

A Beauty parlour is a less formal business that almost always rents booths to a beauty professional who is an independent business owner. 

Think of it as the difference between a "hotel" and a "motel".