Balance  
There are three different types of ways how balance can be identified in an artwork 


Symmetrical  
When on side of the image matches up with the opposite side or makes mirror images,

As you can see if you you cut this image in half (vertically) both sides will make will make mirror images so this picture has balance because its symmetrical. 

Asymmetrical 
  Not symmetrical

This image has balance because this image is asymmetrical or it's not symmetrical
  

 Radial
   Same design from the center 

This image has balance because this picture is radial or has the same design from the center.

  
Pattern 
One element repeated in perfect order

This image has pattern because the element is repeated in perfect order

 Emphasis 
One element that stands out

This image has emphasis because the Mona Lisa stands out

Proportion 
Normal size of things 

The lady is in proportion because it has the normal size

 Movement 
Element that makes your eye move around 

This image has movement because the sky in the background makes your eye move

Variety 
One elements shows all the different type. 

This image has variety because one element (circle 7 color) shows all different types

Harmony 
One type of element is repeated  

This image has harmony because the element circle is repeated

 **Notice how harmony is very similar to variety**

Unity
All 7 elements of art (line, color, texture, value, shapes, forms, space)  are presented.

This image has unity because all of the elements of art are presented in here

Rhythm  
Element repeated in a beat 

This image has rhythm because the top repeats in a beat