Qus: Which is better, MVC or .NET Core?
ASP.NET MVC is the web platform provided by .NET whereas ASP.NET Core is the web platform provided by .NET Core.
.NET Core & ASP.NET Core has been rewritten and supports cross platform scenarios i.e. you can run .NET Core on Windows/Linux/Mac OS. .NET Framework is windows only.
.NET Core is fast since many optimization has been done now.