Your religion is your faith.
So... Christianity is a religion. It's your set of morals, like I said...It's your faith, and where you put your trust.
Spirituality is like the depth of your religion... How much you are in tune with it, how often you live by it.
So if a Christian loves God, obeys His Word, prays, and practices Christian principles, they usually have a deep sense of spirituality.
If they don't do these things often, they have a lesser sense of it.