Microsoft now has .NET Core, .NET Framework and Xamarin (Mono) in its family.
It seems to be a lot of overlap here. What's the difference between these types of .NET Platforms? When should I choose to use .NET Core in my project, instead of .NET Framework or Xamarin?
This is how Microsoft explains it:
.NET Framework is the "full" or "traditional" flavor of .NET that's distributed with Windows. Use this when you are building a desktop Windows or UWP app, or working with older ASP.NET 4.6+.
.NET Core is cross-platform .NET that runs on Windows, Mac, and Linux. Use this when you want to build console or web apps that can run on any platform, including inside Docker containers. This does not include UWP/desktop apps currently.
Xamarin is used for building mobile apps that can run on iOS, Android, or Windows Phone devices.
Xamarin usually runs on top of Mono, which is a version of .NET that was built for cross-platform support before Microsoft decided to officially go cross-platform with .NET Core. Like Xamarin, the Unity platform also runs on top of Mono.
A common point of confusion is where ASP.NET Core fits in. ASP.NET Core can run on top of either .NET Framework (Windows) or .NET Core (cross-platform), as detailed in this answer: Difference between ASP.NET Core (.NET Core) and ASP.NET Core (.NET Framework)
.NET Core is the current version of .NET that you should be using right now (more features , fixed bugs , etc.)
Xamarin is a platform that provides solutions for cross platform mobile problems coded in C# , so that you don't need to use Swift separately for IOS and the same goes for Android.
Xamarin is used for phone applications (both IOS/Android). The .NET Core is used for designing Web applications that can work on both Apache and IIS.
That is the difference in two sentences.
You can refer in this line - Difference between ASP.NET Core (.NET Core) and ASP.NET Core (.NET Framework)
Xamarin is not a debate at all. When you want to build mobile (iOS, Android, and Windows Mobile) apps using C#, Xamarin is your only choice.
The .NET Framework supports Windows and Web applications. Today, you can use Windows Forms, WPF, and UWP to build Windows applications in .NET Framework. ASP.NET MVC is used to build Web applications in .NET Framework.
.NET Core is the new open-source and cross-platform framework to build applications for all operating system including Windows, Mac, and Linux. .NET Core supports UWP and ASP.NET Core only. UWP is used to build Windows 10 targets Windows and mobile applications. ASP.NET Core is used to build browser based web applications.
you want more details refer this links
https://blogs.msdn.microsoft.com/dotnet/2016/07/15/net-core-roadmap/
https://docs.microsoft.com/en-us/dotnet/articles/standard/choosing-core-framework-server
.NET 5 will be a unified version of all .NET variants coming in November 2020, so there will be no need to choose between variants anymore.
.Net Core Class Library is built upon the .Net Standard. .NET Standard you can make only class-library project that cannot be executed standalone and should be referenced by another .NET Core or .NET Framework executable project.If you want to implement a library that is portable to the .Net Framework, .Net Core and Xamarin, choose a .Net Standard Library
(You can make executable project (like Console application, or ASP.NET application) with .NET Framework
It is the new open-source and cross-platform framework to build applications for all operating system including Windows, Mac, and Linux.
Implementation support of .NET Standard[blue] and minimum viable platform for full support of .NET Standard (latest: [https://docs.microsoft.com/en-us/dotnet/standard/net-standard#net-implementation-support])
Source: Stackoverflow.com