What is the difference between XML and AXML in Xamarin.Android Apps?

.axml is nothing more than an extension hack that was used to render Android Layout Files i.e. Android flavored .xml files inside Visual Studio. It literally meant .axml (Android XML).

We previously lacked infrastructure to interpret flavored versions of .xml files coming from all different types of workloads. However in 16.2 and 8.2 respectfully (Visual Studio and Visual Studio for mac), you can use .xml seamlessly in your application and be provided a layout editor, rich intellisense, and more.

If you don't require a layout editor, you have been able to use .xml since the first release of MonoDroid as .axml is processed the same way as .xml at the end of the day.

First, the linker does not do anything with your layout files. So .axml or .xml, it just won't touch it or parse it. The linker only work with the classes represented by the layout files, not the layout files themselves.

Now, regarding the ".axml" versus ".xml" I believe the ".axml" extension is just a legacy thing from MonoDroid. The only goal of that specific extension was probably to identify android layout files, from regular xml files, without any advanced logic (it's only a supposition).

Long story short, if you're facing issues in your project regarding the linker, it's probably not related to your extension choice for layout files. You should keep whatever Visual Studio defines as the default.