The hydro is exactly the same in the brand and the generic. The brand costs more because of the research that went into developing the medication. After a certain period of time the patent on a medication runs out and other companies are allowed to produce and sell the medication, usually at a significantly cheaper price (since they don't have to make up for money spent on research and development). THe generics have the exact same type and amount of active ingredient (ie hydrocodone), although they may use different inactive ingredients. THe difference in inactive ingredients accounts for differences that some people report between brands (ie some cause them to feel nauseous, others don't).