coding wise differenc ASP.Net web api Vs .Net core web api ?

ASP.NET Core supports creating RESTful services, also known as web APIs, using C#. To handle requests, a web API uses controllers. Controllers in a web API are classes that derive from ControllerBase.

1) ControllerBase class

2) Attributes ( HTTP action verb and any known HTTP status codes )

3) ApiController attribute ( Route , Multiple , Assembly )

4) Binding source parameter inference

More Information :

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

https://docs.microsoft.com/en-us/aspnet/web-api/overview/getting-started-with-aspnet-web-api/tutorial-your-first-web-api