Difference between NSwagStudio and Codegen

Hi, I have a Swagger definition in json format and want to generate C# client code so all the boilerplate code is ready to use to make an API call. To be clear I'm the client, the API developer has given us the Swagger definition and the URL.

I saw 2 types of tools that I can use for this: NSwagStudio and Codegen. Can someone explain what's the difference between these two in context of client code generation? It looks like Codegen is more advanced because it also can generate stubs, test classes and the code is more structured I see. In contrast to NSwagStudio, all code is put in 1 file, and there is also no functionality to add/edit headers when calling API's.

Thanks