Juxtaposition

As defined in About.com, Juxtaposition can be defined as placing two variable, side by side and their contrast or similarity are shown through comparison. Many creative processes rely on juxtaposition. By juxtaposing two objects or words next to each other, human brain will automatically associate or transfer meaning. 

Some examples of Juxtaposition: 

Source: http://bookworm.typepad.com/lens/2003/08/juxtaposition.html

                http://strongphotography.wordpress.com/2009/06/11/photo-challenge-winners-juxtaposition/