What's the difference between Windows Store apps (introduced in Windows 8) and Universal Windows Platform apps (introduced in Windows 10).
How much do they share from development point of view. If I spent time learning how to build Windows Store apps can this knowledge be transferred to UWP development?
I would like to just add some more to previous answers.
The main and important thing is that Universal Windows 10 Apps are now compiled to native code (with .NET Native Compiler).
From a developer point of view there is a difference between Debug and Release. When debugging your UWP app in Visual Studio you are running Intermediate Language (with JIT/Just-in-time compilation to machine code) this means fast compilation and deployment. But if you decide to build your app in Release configuration - your app utilizes .NET Native toolchain. This takes much more time to compile, but is optimized a lot more for run time performance.
To read more please see below article:
The second important thing is that Windows 10 is now a Platform. You can create applications and adjust them to work on the different devices. Notice that before in the Visal Studio you created two different UI projects (Windows Phone and Windows) and third project with Shared Code. Now it has changed. Currently it is a single project where you can adjust your UI to different devices at run time. Visual Studio has a new design-time option now to switch between different device screen sizes to see what your app will look like.
There are also Adaptive Triggers and Device-Family folders now - if you decide that for example you would like to create a totally different look for your XAML page on mobile devices - you can use these. Please see below article from my blog:
Please also check this Channel 9 video:
There are also more APIs, as I mentioned previously. To get access to the code specific to the selected platform like Mobile or IoT, you can use Platfrom Extensions. Here is an article where you can read more about it:
https://mobileprogrammerblog.wordpress.com/2015/07/23/universal-windows-platform/
Hope this will help you too and of course your current knowledge is very relevant, so no worries - you will need it! :)