1. Better construction materials: more metal and less cheap, easily breakable plastic.
2. Bottom-mounted PSU design
3. Side-mounted installation for internal 3.5' drives
4. Quick-release mechanisms for the 5.25" drives
5. Engineered for ease of installation of parts
6. Space behind the mobo trays for routing cables
7. Cutouts for routing cables.
8. I could continue but it should suffice to say that they are simply much better cases...