Is there a difference in effectiveness between oxycontin and dilaudid for chronic pain?

Yes: Oxycontin is an extended release drug and will last much longer than dilaudid.

Possibly: In general, any opioid can be as effective as another if carefully titrated to an effective dose. That stated, different opioids bind mu, kappa, and delta receptors differently and each patient's genetics, liver function, and kidney function can affect how they work.

Equal analgesia: Dilaudid is immediate release and will last 4-6 hours. Oxycontin is time release and will last 8-12 hours. It is a time release version of oxycodone. 4 mg of Dilaudid is as potent as 10 mg of oxycodone.

Oxycontin: In equivalent doses they are equipotent. Some people are sensitive to the nauseating effects of Oxycontin and those people would do well with dilaudid.

Narcotic addiction: All narcotics have addiction potential. The more powerful/potent drug, the higher potential for addiction. In general, people are addicted more to short acting opiate than long acting opiate.