What are the most striking ways in which the societies of 1984 and Brave New World differ/relate?
The most obvious similarity is the way both of them treat both the past and language. The past is probably the more obvious. "Who controls the present controls the past; who controls the past controls the future." If the past is malleable, or if the past is unknown (basically the same thing), then it can be used to justify almost any action planned for the future. 1984 goes through great lengths to alter the past to fit the "reality" that the Inner Party leaders/Big Brother wish to create. In BNW, they simply ignore the past, indicating that it has no relevance to the present or the future: "History is bunk."
The problem is that the past does not exist; it's not a place we can go to, check out the facts, and come back with the answers. We only know what we can remember (probably not much and not all that accurately) or what we are told about the past (where does that come from?)
The other is language. We interface with "reality" using groups of symbols we call words. While the meaning of concrete nouns may be obvious/fixed, the meaning of abstract nouns can change because they don't point at anything specific. If you can limit/change the vocabulary ("Newspeak" dictionary), you can limit thought/reality. The only character who has a "vocabulary" in BNW is John; he can speak of experiences in a way that is incomprehensible to BNW citizens.
Another contrast in society is the way in which it is controlled.
In 1984 people are controlled through fear and repression. People are punished if they get out of line. There is no sanctuary free from this - think of Winston and Julia in their "room" ; the paperweight and its fragility show how this is just an illusion of escape.
In Brave New World people are manufactured to adhere to a certain norm. Isn't this a scary forewarning of where we are going with genetic engineering? Also the negation of human worth by using embryonic souche cells... There is no easy ethical answer here, but these are questions which should be raised.
In Brave New World the masses are controlled through gratification rather than repression. The "feelies" - we are getting closer and closer there with 3-D films, sensorial feedback in video games, and even attempts to reproduce and transmit smells.
If you are writing a paper on this topic, you might find it helpful to visit our how-to page at eNotes, "How to Write a Compare-and-Contrast Essay."
In 1984, everyone is unified together against a supposed common enemy that even Winston the story's main protagonist is sometimes influenced by the crowd.
In Brave New World, one is conditioned as they are as they should be as it is right from the beginning based on a factory standard, however they are gratified and not repressed like in 1984.