The Airbus is the larger fleet, and the pairings have fewer legs. It flies pretty much over the entire route map. There are far more "bus only" cities than "E190 only" cities.

The E190 is only East Coast and Caribbean. It is only based in BOS, JFK and MCO. The pairings often have 4 leg days. There aren't many red-eyes, though a few do exist. Since it isn't a growing fleet, the movement has slowed down.