You need to know the original text.
Specific scenes from that text (2 would be good).
Within those scenes you need to know how the language and forms contribute to the play as a whole (ie textual integrity)
And you need to know how (at least) two interpretations have done that scene. ie have they cut lines, what reading have they put on the scene and the play as a whole, its a film what kind of lighting and camara agles have been used etc etc. Obviously the interpretations will have been influenced by the composers context for example Eyre's version can be see as psycoanalytical with a focus on familial bonds due to the rise of divorce in 1993.