I know this seems basic, but I have spent hours looking at docs and videos and cant seem to find the answer. Sorry if I'm being a doof.
Is there a difference between Windows 8 App Store Development and Windows 8 Phone Development? I am not sure if I need to test on both UI's?
J
If you have used the MVVM pattern (like you should) then you likely have separated your XAML and View Models, Models into separate projects. As a result, your non-XAML projects will port over to your Windows Phone 8 app almost 99%. There will be some subtle differences, but not many.
From the perspective of your XAML (or your UI) they simply have to be different because they are different form factors and Windows 8 controls (like AppBar) aren't in Windows Phone 8 and some Windows Phone 8 controls (like Panorama) aren't in Windows 8. As a result, you can't just take your W8 XAML and jam it into WP8 - it would possibly not work and certainly look bad.
Having said that, reusing the same strategies and design you implemented in W8 SnapView is probably a good idea - or at least a good start. But remember, we're talking UI here. Meanwhile, your WinRT-based code is almost completely portable.