A bit confused with the differences between these three models. What exactly is each ones place in Cadillacs lineup. What do they represent as a category? They all look like luxury sedans to me.

Cadillac ATS Render
http://2.bp.blogspot.com/-OM1ziMOVlHs/TXTPm3x8w4I/AAAAAAAAA6I/rL--vOdH6i4/s1600/cadillac-ats-accessories.jpg
Cadillac CTS
http://www.auto-insight.ca/wp-content/uploads/2010/05/2011-CADILLAC-CTS-Pictures.jpg
Cadillac XTS
http://www.automotorblog.com/wp-content/uploads/2010/01/Cadillac-XTS-Platinum-Concept-1.jpg


They all look very similar. What does everyone else think and know?

From what I've read the ATS is the smallest. The CTS is mid sized and the XTS is the largest. Kind of like the 1 series vs 3 series vs 5 series BMW thing.

They all look very similar. Just like how the german counterparts are like. Difference is just size.