They are two different substances. One is a home made unstable chemical that will eat your flesh off your bones
The other heroin. Addictive soul crush drug.
Two totally different drugs.
Desmorphine (pharmacutical) and krocodil (home/street) made are really different.
Krocodil has impurities from being made from chemicals and codeine that will eat your flesh off your bones.
http://en.m.wikipedia.org/wiki/Desomorphine#section_1
Zoeylynn has it down.
There was another thread covering this,
The Drug That Eats Junkies.
Which Sekio might have included in his links. Desomorphine in itself is no more dangerous than any other narcotic. Pharmaceutical Desomorphine which I believe is available in England(?) is basically very similar to Diacetylmorphine (heroin), in that it is more potent than morphine and creates a strong 'rush'. However I have heard from a bluelighter (I forget the name, it should be in one of the krokodil threads on bluelight) that had access to pure Desomorphine, and described it less euphoric than heroin but stronger.
Their is also a possibility that the end result from home made krokodil is not even Desomorphine but another byproduct with some opioid activity such as a-iodomorphide (check out adder's post in the krokodil chemistry link that Sekio provided). Therefore Desomorphine might be the goal when cooking krokodil, but the end result may contain very little to 0 actual Desomorphine and rather other opioids that are a result of the poor synthesis. Not to mention they are not filtering the solution, and injecting whatever opioid they actually come up with, alongside a ton of horrible byproducts used in the production such as iodine and I believe even heavy metals. Add to all that, needle exchanges are pretty much illegal in Russia, and there are no ORT such as buprenorphine maintenance or methadone. This leads to the rapid spread of HIV throughout the IV using drug community.
All in all, this is scary stuff. But if Russia was more liberal in its drug policies, people wouldn't be going to such desperate measures to get high, or probably just alleviate withdrawals. I mean, think about it. In the US, and other countries, people that get addicted to heroin can get on methadone or buprenorphine. But in Russia, this is not really an option. So what does the heroin addict do? Turn to a home made opioid which is stronger than heroin, and about 10x cheaper as well. I am also unsure about what kind of access drug users even have to harm reduction resources, but I imagine your average krokodil user has long ago sold their computer, if they even had one to begin with.
In my eyes it goes like this:
user becomes addicted->user can't afford heroin any longer, or can't find it->there is no Methadone. There is no buprenorphine->out of desperation, the Dependant person, with little education on krokodil turns to it as a heroin substitute.
Believe me, this is not a trend that is going to pass on to other countries. This is the tragic product of a country with fucked drug policy's. At least that's my oppinion.