Strength in Differences?

I am doing some research for an article I am writing and came upon an interesting quote from Ari DiFranco.  It states:

"I know there is strength in the differences between us; I know there is comfort where we overlap."

This got me thinking more about similarities and differences.  Years ago (1995) I wrote a book titled, "Beyond Difference."  In this work I postulated that our differences push us apart - that this action is bore from our defense mechanism of caution, or even flight from that which we don't see as similar or do not understand.  I argue in the book that our differences create a wedge between us and the only way we can move forward in relationships is to find more similarity and just let our differences be.

Then I considered this quote from DiFranco and it challenged me to think deeper on this notion of differences.  I get the "comfort in overlap" as our similarities do create bridges in connection.  They give us something to talk about and to build upon. 

But in the quote, he also suggests that there is strength in our differences - a position that I had not considered.  It caused me to go a bit deeper on this issue.  What is it about difference that might promote strength?  Is it in the fact that the differences might cause us to think deeper - or to put ourselves in the different person's shoes?  Or, does it suggest that the difference makes us feel superior, and in a way, stronger (or better) than the different person.  And in all this, how does the process create strength?

I am still pondering this notion, but I wondered what you might think.  Is there strength in difference?  When we encounter people who are different from us does this make us feel stronger - and if so, how?