Fentanyl is more powerful as well as faster acting than hydromorphone (Dilaudid). Hydromorphone is longer lasting though so more effective for pain management where Fentanyl is better for emergency administration.
Dilaudid is about twice the strength of morphine. Fentanyl is 100 times the strength of morphine to give you an idea of the potency. Both are similarly addictive.
Hydromorphone is an opioid derivative where Fentanyl is completely synthetic requiring no opiates.
I have taken Dilaudid and it is a very impressive sensation. I have never received Fentanyl but administer it relatively frequently.
Both pale in comparison to Carfentanil. That’s generally used to sedated large mammals.