These are different versions of the same development platform. The .NET Framework is a very old platform that runs only on Windows. The .NET Core is a newer platform that can run on both Windows and Linux. Starting with version 5, .NET Core has been renamed to just .NET with a version number. And only the ASP.NET Core framework for creating web applications has the “Core” prefix. Admittedly, Microsoft has a rather complicated history of naming the same product from version to version, so it is not surprising that many people find this confusing.