I am new to this environment but I got confused a bit, when I see these 3 kind of apps. I assumes that Windows Store App is an app that goes on the market place, but also the WP app does that ... and what about Windows Phone Silverlight? Thanks
So there is the "Windows Phone Store" containing "Windows Phone Apps" and the "Windows Store" containing "Windows (8.1) Apps" for tablets, notebooks etc.
The only thing interesting here is that apps can also be "universal" which means they are available both in the Windows and Windows Phone store and can be downloaded in one of them for free if you bought them on the other platform.