How do you define mission?

I read with great interest the articles related to church renewal.  It deserves our full attention if the church is to survive and thrive.  Is there a difference between a “mission” and a “church,” and how are they related? It seems to me it has a lot less to do with “store fronts, pubs and praise bands versus Victorian Gothic and organs” and a lot more to do with where we turn for the definitions that will shape our future.