Since VS2019, I have noticed that every new project has regular XML as its resources like native Android Studio applications, but previously (2015 or 2017) it created AXML files.
Internally, the files looked exactly the same. However, I have recently started to get linker errors (as reported in .NET for Android issues #3376 and #3387), which made me wonder if they have anything to do with the change from AXML to XML.
Are there specific differences between these formats?
.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.