It's been said, but let's consolidate:
Cinema Displays:
Plastic 20'', 22'', and 23'' LCDs (Older)
Aluminum 20'', 23'', and 30'' LCDs (Current)
Studio Displays:
Plastic 17'' LCD (Old)
The old CRT lineup
So the basic difference is, cinema displays are widescreen and studio displays are not. All of the cinema displays are LCDs, but most of the studio displays were CRTs.