You do realize if you have ever had a morphine drip in the hospital you have basically done heroin intravenously, right?
"Morphine" as it is commonly referred to, is morphine sulfate. Heroin is diacetyl morphine. That is, heroin is simply morphine with an acetyl molecule attached.
In terms of effects, they are exactly the same -- and medically interchangeable -- except for dosage. In fact, they are both converted to the same form of morphine when they get into the body.
The only significant difference between them is that the acetyl molecule allows heroin to cross the blood-brain barrier more quickly than ordinary morphine. The result is that, in terms of dosage, heroin is about three times stronger. That is, one grain of heroin equals about three grains of morphine.
I am not advocating drug use, or debating legalities. I was simply pointing out a fact.