What is the difference between the way Catholics view The Blessed Virgin Mary and Unitarians view Jesus?

Reading chats and posts and such here with our BU friends I've noticed a thread that seems similar to the way Catholics view The Blessed Virgin Mary and Unitarians view Jesus. It seems like in both theologies they're asymptotically approaching God/Divinity. Could someone help me compare and contrast the relations between the two? Basically, what is the difference between Unitarian Christology and Catholic Mariology?