.NET Framework is the traditional version of the .NET platform, primarily targeting Windows applications. It is mature and offers extensive libraries and tools. On the other hand, .NET Core is a cross-platform that allows developers to build applications that run on Windows, macOS, and Linux. It is modular, lightweight, and designed for modern application development. With the release of .NET 5 and later versions, Microsoft merged the features of both frameworks into a unified platform called .NET, which combines the best of both worlds.