Sorta what DManley said;
I've used both, but have shellplates and shell holders for both and find them interchangeable for the 9mm.
I've loaded .40, 10mm, .38Super, 9x21, and of course 9mm all with the same shell plates and no difficulty.
I've also used the priming arm for my Lee Classic with both also.
I prefer the #19 as it's more friendly (or forgiving if you will) with the wide variation in the case tolerances of various makes of 9mm.