As to what gives us a sense of purpose in life, I believe that it is more similar, than it is different; especially if you are a child of God (a Christian.) 

As for me, having a personal relationship with God is the most important thing in my life; closely followed by my family.  Everything else pales in comparison to these two things.  Knowing that God loves me and allows me to be involved in His life is very important to me.  Being able to share God's love with others and spending time with my family is why I am here.  God gives me peace and purpose in the present, and hope for the future.

I do not believe that anyone will ever have a true sense of purpose until they have God in their life.  The emptiness in our hearts can only be filled by God; He has placed it within so that we will search for Him.