ASP.NET Core is the successor of ASP.NET, which was also open-source web framework, developed by Microsoft. ASP.NET is a web framework that is modular and could run in both the .NET framework and the cross-platform .NET core. However, ASP.NET from its version 3 has stopped supporting the .NET framework and now only supports .NET Core. This framework could be used to build dynamic websites and web applications to facilitate better UI/UX.
If you wish to learn more about .NET and want to get certified then check out the .NET certification course from Intellipaat. Also, have a look at our YouTube video on .NET Tutorial.