Brand name and generic name differ in price. Most generic items are very similar to their brand name counterparts but cost substantially less.
For example, many over the counter medicines like Tylenol and Night Quill for example also have generic brands that offer the exact same ingredients and are a lot cheaper.
Wal-dryl is the generic version of Night Quill and is sold for a few dollars cheaper. Sometimes the generic brand is just as good as the name brand and it is cheaper because the generic brand has no advertising costs associated with it.
Other times the generic equivalent may not be as good. For example, when buying paper towels I always feel that the generic brand comparison does not compare to the name brand because the generic brand is lighter than and not quite as absorbent as the brand name paper towels.
I found that the same hold true for bathroom tissue as well.