Amazon Hi Res

1. My source is Amazon Hi Res. When using the BlueOS app I have noticed some tracks have a resolution of 'CD' but when I use the Amazon App they are available in 'HR'. Can anyone clarify why BlueOS seems to be using a lower resolution than the Amazon app?

2. I can either play directly through the BlueOS app, or just from my device (e.g. phone) and stream to the the Node 2i through Airplay. Does anyone know if this affects the quality i.e. is quality via Airplay less than directly through the App