PCL vs SCL

Recently I've found that the Portable Class Libraries are becoming obsolete and the new "better way" is to use the Standard Class Libs.

https://docs.microsoft.com/en-us/dotnet/standard/net-standard

So the question is: which should I use? Should I care at the moment about those 2 or just stick to the PCL?
Are there any crucial differences when coding the SCL?

Let's discuss