setImageDrawable vs setImageResource vs setBackground

package com.example.androidsetimage;

import android.os.Bundle;
import android.app.Activity;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
  ImageView image1 = (ImageView)findViewById(R.id.image1);
  ImageView image2 = (ImageView)findViewById(R.id.image2);
  ImageView image3 = (ImageView)findViewById(R.id.image3);
  TextView text4 = (TextView)findViewById(R.id.textview4);
  Button button5 = (Button)findViewById(R.id.button5);
  EditText edittext6 = (EditText)findViewById(R.id.edittext6);
  
  image1.setImageDrawable(getResources().getDrawable(R.drawable.ic_launcher));
  image2.setImageResource(R.drawable.ic_launcher);
  
  //Requires API 16
  image3.setBackground(getResources().getDrawable(R.drawable.ic_launcher));
  
  //deprecated
  text4.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_launcher));
  
  button5.setBackgroundResource(R.drawable.ic_launcher);
  
  //Requires API 16
  edittext6.setBackground(getResources().getDrawable(R.drawable.ic_launcher));
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#303030"
        android:textStyle="bold|italic"
        android:text="android-coding.blogspot.com" />
    <ImageView
        android:id="@+id/image1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <ImageView
        android:id="@+id/image2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <ImageView
        android:id="@+id/image3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/textview4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView 4"/>
 <Button
        android:id="@+id/button5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button 5"/>
 <EditText
        android:id="@+id/edittext6"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Hello android-coding"/>

</LinearLayout>