Externally the two models differ in some details of the front panel, particularly in the way the front interface connectors are placed:
Compare also the LED indicators and Power/Reset buttons:
The shape of the 5.25” bay door is different, too:
This door is better designed on the Bach. The Mozart’s is bigger and the Bach’s is lighter, easier to open up and covers only the drives bay. Well, you won’t need to open the door up too often because both the cases come with special faceplates for optical drives. It is a classic flip-down spring-loaded panel on the Bach:
It has a metal prop to fix it in the closed position and you can also adjust the strength of the spring as necessary:
It’s simpler with the Mozart:
The plate which is secured with two metal brackets in the snapshot is simply glued to the drive tray with the included two-sided scotch tape and serves as a decorative faceplate as well as a kind of tray extension. We can’t unfortunately illustrate this as the mentioned two-sided scotch tape holds so strong that the drive you attach the faceplate to will become an integral part of the case, so you should choose one carefully.