Materials aside, these two cases have a lot in common. They both protect the entire iPod nano save for its Hold switch, headphone port, Dock Connector, and one part of its face: Mypod covers the nano’s screen with a clear protector while exposing the Click Wheel, and iStitch covers the Wheel with fabric while exposing the screen. Both cases slightly limit headphone and Dock Connector access; the plastic Mypod isn’t compatible with oversized…