.NET Framework vs .NET Core vs .NET: Key Differences in C#

.NET Framework is the original Windows-only platform for building C# apps, .NET Core is a cross-platform, open-source, and faster version, and .NET (also called .NET 5+) unifies both into a single modern platform for all app types.

Quick Comparison

Here is a quick side-by-side look at the main differences between .NET Framework, .NET Core, and .NET.

Feature	.NET Framework	.NET Core	.NET (5 and later)
Platform Support	Windows only	Windows, macOS, Linux	Windows, macOS, Linux
Open Source	No	Yes	Yes
App Types	Desktop (WinForms, WPF), Web (ASP.NET)	Web, Console, Cloud, Microservices	All app types including Mobile and Cloud
Performance	Good but older	High performance and optimized	Improved performance over Core
Release Status	Legacy, no new features	Supported until .NET 5	Current and future platform
API Surface	Large Windows-specific APIs	Smaller, modular APIs	Unified and expanded APIs

Key Differences

.NET Framework is the original Microsoft platform released in early 2000s, designed only for Windows desktop and web apps. It includes a large set of Windows-specific APIs and supports technologies like WinForms and WPF for desktop apps. However, it is closed-source and no longer actively developed with new features.

.NET Core was introduced later as a cross-platform, open-source rewrite of .NET to support Windows, macOS, and Linux. It is modular, lightweight, and optimized for modern app needs like cloud and microservices. It supports console apps, ASP.NET Core web apps, and more, but initially lacked some desktop support.

.NET (starting with version 5) unifies .NET Framework and .NET Core into a single platform. It supports all app types including desktop, mobile, cloud, and IoT with improved performance and a consistent API. This is the future of .NET development, replacing both older platforms.

Code Comparison

Here is a simple C# program that prints a greeting, showing how you would write it in .NET Framework.

csharp

using System;

namespace HelloWorldApp
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello from .NET Framework!");
        }
    }
}

Output

Hello from .NET Framework!

.NET Core Equivalent

The same program in .NET Core looks almost identical, showing the shared C# language and runtime features.

csharp

using System;

class Program
{
    static void Main()
    {
        Console.WriteLine("Hello from .NET Core!");
    }
}

Output

Hello from .NET Core!

When to Use Which

Choose .NET Framework if you have existing Windows desktop apps using WinForms or WPF that rely on Windows-only APIs and you do not plan to migrate soon.

Choose .NET Core if you want cross-platform support and are building new web, cloud, or console apps but are not ready to move to the unified platform.

Choose .NET (5 or later) for all new projects to get the best performance, cross-platform support, and future-proof features across desktop, mobile, web, and cloud.

Key Takeaways

.NET Framework is Windows-only and legacy, best for existing Windows desktop apps.

.NET Core is cross-platform and open-source, ideal for modern web and cloud apps.

.NET (5+) unifies both platforms and is the recommended choice for new development.

All three use C# but differ in platform support, APIs, and performance.

Migrating to .NET (5+) future-proofs your applications with latest features.