Both medications are highly effective hormone therapies for prostate cancer, but they contain different generic active ingredients. Leuprolide is one generic drug, while the other injection you mentioned contains the generic drug triptorelin. Although they are different molecules, they belong to the exact same class of medicines called GnRH agonists. They work in the same way by lowering testosterone levels to slow the growth of prostate cancer. Clinically, they are equivalent in efficacy and safety. Your father's oncologist may prescribe one over the other based on availability or dosing schedules. Both are standard, reliable treatments, so there is no need to worry.