Hi, @helenfrances - this is an excerpt from a Mayo Clinic article featuring a Q&A with an anesthesiologist for a trauma professionals enewsletter. This response relates directly to your question on dependence versus addiction:

Q: Is there a difference between physical dependence and addiction?
A: Yes. Physical dependence on an opioid occurs in humans and in lab animals. It happens when a patient has received opioids for approximately five days or more and develops withdrawal symptoms — such as tachycardia, goose flesh, diarrhea or diaphoresis — when the drug is withdrawn.

It is very different from addiction, which is drastic behavior an individual exhibits to obtain opioids, such as stealing medications, buying street drugs to treat pain or engaging in risky behavior in exchange for drugs.

The whole article has information that might be of interest on the opioid epidemic from the point of view of a pain specialist https://www.mayoclinic.org/medical-professionals/trauma/news/treating-pain-responsibly-in-the-midst-of-an-opioid-epidemic/mqc-20438006.