Hello RHuet,   Your question is an easy one!  There is no difference between the two medications.  One is a generic name (the isosorbide dinitrate) and the other (Isordil) is the brand name.   People often wonder if there is any difference in potency, action, safety, etc in generic medications.  The short answer is no.   Generic medications in the USA are regulated to the same standards as brand name drugs.  And if fact, part of the approval process in the FDA requires companies to prove bioequivalnce.  This does not mean that they down to the atom the same compound, but, it does mean that generic manufacturers must demonstrate the drug has the same actions in the body as the brand name.   Hope this helps.   To your health, Neil MD