Desktop Streaming – Is for just that desktop or laptop (larger screens). This will give you and smooth stream while your browsing without shutting off, it does not show cover pics.
Mobile Stream – The same as a desktop or laptop only made for mobile phones, no cover pics and you get the uninterupted stream. 
Mobile App -Gives you the same with the exception of 2 things; You don’t have to be on the website at all and you see cover pics of the songs if they are available. It is a free app that you will have to download from Google Play.