[MeinBlutIstBlau]

It's like .Net Framework and .Net Core. It looks the same but Framework was closed source iirc and Core is open source and newer.

[jmkni]

And then we have .net 5, which is dotnet core, but they've dropped the 'core' part

[solarkraft]

Don’t forget .NET Standard. There’s also Xamarin’s Mono flavor, which attempts to implement Framework’s API.

Yeah, it’s a mess. Just remember that .NET 5 is a significant break from legacy and the future.