I'm working on a behind-the-scenes library for Windows Phone 8. We need to use the filesystem as a crude cache. I've found that there are two APIs for Windows Phone 8 though. There is the typical IsolatedStorageFile API that was carried over from Windows Phone 7. However, there is also now the new Windows.Storage.ApplicationData set of APIs which I assume are carried from WinRT.
Which one should I use? What are the differences and why should I use one or the other? Also, how do they interact? If I create a file in IsolatedStorage, can I see it in Windows.Storage?