As hard as it may be to believe, they are actually the same color. (See the second picture directly below with the surrounding colors removed.)
I think this optical illusion is a wonderful metaphor for how all of us--myself included--see the world. We like to believe we are seeing the world objectively but the reality is that our vision is heavily influenced by the beliefs, assumptions and ideas which occupy our minds and thus distort what we think we are seeing.
Next time you are quick to judge a person or a situation, remember this optical illusion and ask yourself: Are you really seeing reality or just your perception of reality?