The new version includes significant language and platform extensions for C #, Visual Basic, and F #, that simplify the creation of asynchronous code, provide a mixture of control flow in synchronous code, increase the responsiveness of the user interface and improve the scalability of web applications.
Microsoft's new software platform also implements significant enhancements in other functional areas, such as ASP.NET, Managed Extensibility Framework, Windows Communication Foundation, Windows Workflow Foundation, and Windows Identity Foundation.
Microsoft .NET Framework 4.8 provides enhanced performance, reliability, and security.
More details can be found in the official documentation - https://docs.microsoft.com/en-us/dotnet/framework/whats-new/#v48