I ran into this the other day. I couldn't justify paying $5 for the Android app.
It's essentially a simpler interface to our web service. The same one used by the web app. So results should be the same from both. But you cannot see an article preview or edit the article's title as you can with our web app.
Oh, and thank you for submitting this here, btw. Was surprised to see it. :)
I was never able to use the Android app properly because it didn't allow me to use my kindle account. My account goes something like this name@kindle.com . But the Android app always added name@free.kindle.com.