That is an interesting question. I checked out Drugs.com -a good source for Drug information. If you punch in Morphine you get a generic description of the drug. If you punch in morphine sulfate - you bring up both the generic description of the drug as well a link to Morphine Sulfate or Extended Release Morphine. When the pharmacology of the morphine sulfate is described the page refers to 'morphine', though, not morphine sulfate. This suggests to me that the two drugs have the same effects but that morphine sulfate is delivered in such a way as to have longer-lasting results.
Thank you. Looks like they are pretty much the same drug. Interesting. I am dealing with a lady who claims to be allergic to morphine, yet is taking morphine sulfate. I smell a rat!