This virus has at least 2 strains, if not more. The one in Italy is way deadlier than the one in S. Korea. 10x seems to be the bare minimum. 34 times seems to be the average for now.
The difference between Italy and South Korea is not about two different strains, it's about the different method of testing.
Korea is doing testing on a massive scale in order to contain the virus, they had already done 320.000 tests by the end of the last month. Italy had done under 50.000 with a bigger population by March 8th. It just means that Korea is picking up even the milder cases to make sure to take the right measures to stop the spread.
In Italy the testing capacities are overwhelmed, especially in the most affected regions, so the real number of cases there is actually much higher.
Unfortunately the same goes for the rest of Europe as well as many countries are still only testing people with very extreme symptoms. Around 100.000 people from Slovakia have been to Italy since mid-February and despite that so far they are only testing people who have a temperature over 38 degrees Celsius and had traveled to the affected regions and some people who were in contact with the confirmed cases. We have only 21 confirmed cases as of today (jumped up from 10 yesterday, 2 in serious condition) so far, but everyone is aware that the real numbers would tell a different story.
And in the Czech republic they have jumped over 100 confirmed cases today (2 in serious, 1 in very serious condition), but just like Slovakia they only tested very few people so far. After today, they are upping the scales of the testing a lot and over the weekend they're getting the quick test kits from China. I fear it's pretty much a given that by start of next week the number of diagnosed people will have grown significantly.
Oh, and by the way, I'm saying that they have been testing too few people in Czech republic (around 1600 tests for a nation of 10 million) and Slovakia (around 800 tests for a nation of 5 million), but actually the US with a population of 300 million had only tested 1707 people by March 7th:
The thing is that at the moment no one knows how many people are really affected by the virus either in Europe or in the US.
And the response from some European countries so far is very weak and non-existent from the European Union. It's strange when you have small central/eastern European countries taking nationwide measures like closing schools and cancelling events and even stopping international transit of people sooner than Germany. It's because we have seen that Europe has done precisely nothing for Italy in their direst hour and we had to decide that closing ourselves off is the only solution.
Also, if anyone believes that Trump's ban on travel from Europe will protect the US, I fear they are mistaken. Oh, and it's funny how the ban doesn't apply to the UK where they have around 600 confirmed cases and even Boris Johnson has admitted today that the real number is up to 10.000 there.