I think a better question might be why is S. Korea’s numbers better than Italy.
South Korea took strong measures to get a handle on the disease early, and did not have to engage in triage.
Italy also has a higher population of older and obese people than South Korea.
However, South Korea has just hit the pause button, they have not stopped anything.
If they start celebrating victory too early, the virus will have the last word.
Different strain perhaps. The Italians may have gotten the bad mutated one. While SK got the original non mutated Bat jumping virus. Or the Chinese may have released multiple strains to hide a more virulent modification.
Only one reason: South Korea took it seriously and almost immediately instituted measures to slow down it's spread so that their healthcare wouldn't be overwhelmed. They did more than what we are doing right now. Italy on the other hand did almost nothing initially. That's the only factor.
Have you been to Italy? That is the most affectionate but disorganized country imaginable. Even if it's not crowded, they get close to talk with you. And they can't even make their trains run on time - except during WW2, and that got awkward for them. BTW, I love Italy, but it's the love that comes from knowing their flaws too.