Aroma - a Christian perspective
Christians are described as bearing the "aroma" of Christ in the world; some who hear the Gospel will be receptive to it and others won't. It's an unusual metaphor, but one that fits the Bible's depiction of Christians as ambassadors of Jesus to a sinful world.
Fragrance - a Christian perspective
The knowledge of God is described as a pleasant fragrance--a smell that Christ-followers spread through the world when they spread the good news and do good works in Christ's name.