Android beginner difference between padding and margin

Padding is for inside/within components. Eg. TextView , Button, EditText etc.
Eg. space between the Text and Border

Margin is to be applied for the on-outside of the components.
Eg. space between left edge of the screen and border of your component

Visual representation is great in : Difference between a View's Padding and Margin

With Padding, i have seen a difference in 2.2, 2.3 and say 4.3, 4.4
in such cases:

<RelativeLayout 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"
    tools:context=".MainActivity" >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:text="ASDFGHJKL" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingLeft="15dp"
        android:text="@string/hello_world" />

</RelativeLayout>  

Also, check the use of dimens:
http://developer.android.com/guide/topics/resources/more-resources.html

Margin

Margins make up the vertical and horizontal areas between elements. If elements have no margins around them, they will bump right up against each other. In other words, he space outside of, or between, elements is what comprises the margin areas.

Padding

The padding of an element is the horizontal and vertical space that’s set around the content area of the targeted element. So padding is on the inside of a box, not the outside.