What is the difference between .NET Standard and PCL (Portable Class Libraries)?

.NET Standard and PCL profiles were created for similar purposes but also differ in key ways.

Similarities:

• Define APIs that can be used for binary code sharing.

Differences:

• .NET Standard is a curated set of APIs, while PCL profiles are defined by intersections of existing platforms.
• .NET Standard linearly versions, while PCL profiles do not. PCL profiles represents Microsoft platforms while the .NET Standard is platform-agnostic.