Thank you for coming back and providing the requisite information.
You have asked a couple of questions, so I’ll answer them accordingly.
Can you please give me to right DLL?
I will recommend using the GroupDocs.Comparison for .NET API for your application. As I mentioned earlier, the API is totally UI-independent(can be used in any .NET project), backend API which can be easily integrated into an ASP.NET application. Please visit the API’s documentation to have a better idea about the features supported by the comparison API.
Is there any sample project for ASP.NET application for comparison.
Did you check out the showcase project, hosted on github, I shared with you earlier? It contains some sample ASP.NET applications for comparison as well. Please download the github project and run the sample applications at your end for a better understanding of integrating the API in a .NET application. Also, check out the documentation of these front-end showcase projects for a detailed overview of how the applications are built using the API.
Please visit the following links. Hopefully, these links will prove out to be helpful in this regard:
2- Nuget Package
3- Github source code examples(Showcase project contains your required examples)
4- MSI Package and Zipped DLLs
Please let us know in case you find something ambiguous.