Isn't it that there are two main strains, one (30% of cases) is less lethal (and this one is predominant in South Korea) and the other (70% cases) is e.g. in Italy?
Two strains source: https://www.newscientist.com/article/2236544-coronavirus-are...
Two strains source: https://www.newscientist.com/article/2236544-coronavirus-are...
There are more than 100 strains, which you can see here: https://nextstrain.org/ncov
http://virological.org/t/response-to-on-the-origin-and-conti...