What are key differences between .NET Framework and .NET 8+ (.NET Core)?

Here’s a clear comparison of the classic .NET Framework vs. modern .NET (a.k.a. .NET Core / .NET 5+ / .NET 8) so you can see how they differ:

Feature / Aspect	.NET Framework	.NET 8+ (a.k.a. “.NET Core” family)
Release history	2002 (v1.0) → last major version 4.8 (2019). Now in maintenance mode.	Started as .NET Core 1.0 (2016). Unified into “.NET 5” and now continues as .NET 6/7/8…
Platform support	Windows-only (depends on Windows APIs).	Cross-platform: Windows, Linux, macOS, plus containers.
Architecture	Monolithic runtime + libraries installed at the OS level (Global Assembly Cache, machine-wide).	Modular, self-contained runtime—you can bundle the runtime with the app.
Deployment	Needs the correct .NET Framework version pre-installed on the machine.	Can publish as self-contained (no system-wide install) or framework-dependent. Great for Docker.
Performance	Older JIT, larger memory footprint.	Modern JIT (RyuJIT), better GC, ahead-of-time (AOT) options → significantly faster.
APIs / Libraries	Full Framework APIs including older Windows-specific ones (WCF server, WebForms, System.Drawing tied to GDI+).	Unified Base Class Library (BCL). Adds new APIs, Span<T>, minimal APIs, modern async I/O. Some legacy APIs missing or replaced.
App models	ASP.NET WebForms, WCF, Windows Forms, WPF (Windows only).	ASP.NET Core, Blazor, MAUI (.NET Multi-platform App UI), modern console & worker services.
Tooling	Works with Visual Studio on Windows.	Works with Visual Studio, VS Code, JetBrains Rider on Windows, macOS, Linux.
Open Source	Mostly closed source (some parts later opened).	Entirely open source on GitHub, community-driven.
Long-term future	Only security/bug fixes. No new features.	Actively developed: new releases every year (LTS every two years).
Cloud & containers	Possible but heavier.	Designed for cloud-native & microservices, excellent container support.

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Key Takeaways

• Use .NET 8+ for new projects.

  • Cross-platform, faster, actively evolving.

  • Ideal for microservices, cloud, containers, web APIs, and modern desktop/mobile with MAUI.

• .NET Framework only for legacy apps that depend on Windows-only tech (e.g., classic ASP.NET WebForms or WCF server features) and can’t easily migrate.

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In short:

• .NET Framework = Windows-only, legacy, maintenance mode.

• .NET 8+ = cross-platform, high-performance, future of .NET.