We cannot write your essay for you, but we can help. First of all, in discussing differences, you must determine whether you are reading the drama or watching it (drama is meant to be viewed, not read, for the most part). If you are reading the drama, the differences are less, because reading makes a dramatic work more novel-like.
That said, looking at drama as a performance, athough many of the elements of fiction are the same in drama and in novels (characters, plot, theme, setting, etc.) the way we arrive at a knowledge of these elements is different. When reading a novel, an author can write pages and pages of descriptions, whether it is about a character or whether it is about a situation. When writing a drama (to be performed), this would make the play extremely boring. So, the dramatist must take this into account and write dialogue for the characters that is both interesting, fast-paced, but meaningful. The dramatist must put the character into situations that reveal his character, whereas a novelist can do this, but in addition, can also write about the character.
Dramatists do have techniques that they use to give additional information about their characters. For example, Shakespeare uses long monologues called soliloqueys in which we can get an insight into the character. If you have read and then watched any Shakespeare plays, you may have noticed that you got more out of watching the plays but were confused when reading them. This is because, in spite of the difficulty of the language, you can pretty much figure out and appreciate what is going on when watching the play because of the actors' skills, special effects, etc., whereas when you reading the play, all you have is your own imagination and that is often not enough with Shakespeare because of the Elizabethan language.
Think about it this way. Have you ever read a book and then seen the movie version and commented, "Gee, they left out that important part where..........." well, when being adapted for film (which is drama), not everything in the novel works on screen. It would make a long, and boring, film to include everything that is in the novel.
That is one important element. There are others, and perhaps some drama experts can give you additional information.