What is the main difference between asp. Net and asp. Net core?

Question

I am confused can anyone help me

Answer 1

Read the docs, its explained here.
ASP.NET Core is the new name of the last version of Microsoft's unified web frameworks, to create web apps and apis.

https://docs.microsoft.com/en-us/aspnet/core/introduction-to-aspnet-core?view=aspnetcore-3.1