What are the benefits of oxycodone rather than hydrocodone?

The only difference is the potency of the drug - Oxycodone is a stronger opiate than Hydrocodone is. For a pain patient, the decision to move to a stronger drug is usually based on the lower strength drug not being able to do the job in current doses, or if the patient has to take more to deal with the pain. Fewer doses of a drug to deal with a problem is always more preferable to having increase the dose of one that isn't working as well.