Difference between getInfoWindow() and getInfoContents() in Googlemaps v2 for Android
In the above screenshot, I have used an InfoWindowAdapter, where I overrode getInfoContents(). My getInfoContents() method returned the icon and text that you see. My getInfoContents() did not provide the rectangular bubble that the icon and text is in. Also, my getInfoContents() did not provide the caret at the bottom of that bubble that points at the marker, the slight drop shadow behind the bubble, etc.
So, you use getInfoContents() if you want that rectangular bubble, caret, drop shadow, etc. If you do not, and you want to provide the complete info window visual representation, use getInfoWindow().