Difference between a clickable ImageView and ImageButton

I'm just wondering if there is any significant difference between an ImageView that's set to be clickable, compared with an ImageButton?

Is there any reason for using one over the other? Is there any restriction on the drawable for an ImageButton that leaves ImageView as the only possible option?

Will I possibly lose any functionality of a button if I opt for a clickable ImageView over ImageButton?

There's no differences, except default style. ImageButton has a non-null background by default.

EDIT: Also, ImageButton.onSetAlpha() method always returns false, scaleType is set to center and it's always inflated as focusable.

Here's ImageButton's default style:

 <style name="Widget.ImageButton">
     <item name="android:focusable">true</item>
     <item name="android:clickable">true</item>
     <item name="android:scaleType">center</item>
     <item name="android:background">@android:drawable/btn_default</item>
 </style>

ImageButton is inherited from ImageView

public class ImageButton extends ImageView {
public ImageButton(Context context) {
    this(context, null);
}

public ImageButton(Context context, AttributeSet attrs) {
    this(context, attrs, com.android.internal.R.attr.imageButtonStyle);
}

public ImageButton(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    setFocusable(true);
}

@Override
protected boolean onSetAlpha(int alpha) {
    return false;
}

@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
    super.onInitializeAccessibilityEvent(event);
    event.setClassName(ImageButton.class.getName());
}

@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
    super.onInitializeAccessibilityNodeInfo(info);
    info.setClassName(ImageButton.class.getName());
}

as @Micheal describe i just add details to his answer