Fine as a blanket statement, but if that were fact, what would all the other opioids be there for? Some people respond better to certain drugs; morphine is the gold standard but not the unequivocal #1. In the UK I'm told many hospitals use diamorphine as a first-choice full agonist, with morphine as plan B, due to a more benign side effect profile and greater potency.
Anyway there's plenty of comparison charts online, most of which are fairly uniform and accurate. Just take into account the varying bioavailabilities of different drugs and routes of administration, and that certain opioids (like morphine) will be more sedating at equianalgesic doses than others (like oxycodone) and may thus feel slightly stronger.