Difference between src and background for image view [duplicate]

Answer 1

Background will fill all avaliable place of view, src - will paste image and scale/positioning using ImageView parameters. For example, parameters "scaleType", "scaleX", "scaleY", "gravity", "adjustViewBounds" will affects only on src image

Answer 2

But both are looking differnt

First, the drawables are different.

Second, the background always scales to the size of the view.

when i press the imageview with background set it is not showing the selection. can anyone explain why this happens

The selection effect is because by default, the background is a StateListDrawable with a different appearance in state_pressed. Your custom background looks the same in all states. You can create StateListDrawables in xml with a selector.