The rail back is the easiest back to make. The bar back is essentially no different to the rail back in manufacture though it may be more likely made on a milling machine rather being ground. On a bar back the raised 'bars' are about equal width to the hollows. Rails are about half the width or smaller. The portculis back is a rail back ground in both directions.
Ring backs are the least common of the four main types but nevertheless there are many variations.
They would all need to be made on a lathe. They seem to be more often found on majolica tiles, perhaps as the engineering company who made the pattern dies could easily produce the back dies too. Just the rail back is shown but the same applies for bar and portculis backs too. The corners are recessed on this drawing, this innovation occurred when tiles became used in furniture and various types of frames and was to facilitate easier corner fixing. Recessed corners were often used on bar and ring backs too.