What is the difference hydromorphone and methadaone?

Hydromorphone is the generic name for Dilaudid, it is a derivative of morphine, to be specific, a hydrogenated ketone thereof and, therefore, a semi-synthetic drug. Methadone is methadone, a synthetic opioid, used medically as an pain reliver, antitussive and a maintenance anti-addictive for use in patients on opioids or who have long term chronic pain issues.