The washer sprays a wide fan shaped spray of water that covers half the windscreen instantly while the 2 hole version sprays 2 narrow jets which the wipers have to spread. I don't know why all cars do not have fan spray jets as the cleaning action is almost instant which is safer than 2 ill adjusted narrow sprays that never put the water in exactly the right place. In my last cars I always changed the jets but with my XC70 I didn't know which units would work because of the heating of the spray heads which is why I'm seeking advice on part numbers to find a plug and play jet.
Or they are giant jet aircraft engines with huge frontal fans operating like shrouded propellers in addition the the propulsion of the rear jet efflux.
