I am better at lit than I am at English.
If you like to critically analyse the intentions of a writer when he/she creates their text, and talk about how they do these things, then you should pick lit.
If you like, however, scratching the surface and talking in general about the themes and ideas that are presented to the reader through the creation of a text, and their greater meaning, then you should pick English.
I do both. We are not allowed to pick Lit over English.
In answer to your question:
In the lit exam, you write two essays. You choose two texts from the lists provided to you from two different areas or genres, for example a play and a novel, or poetry and short stories.
Each text has three passages that are selected from anywhere in the text.
You have to analyse these passages and reference at least one when you formulate a "discussion of the given text".
So basically, you're talking about what the writer is saying and how they go about saying it with reference to literary techniques, using what you are given as a basis for example. In lit you will probably study around five or six texts, one of which will be a text you cannot choose for your exam.
The English exam is longer, because it contains an extra essay. You do study fewer texts, because you have the language analysis component which takes up a third of the exam. There are three components to the exam: Language Analysis, Text Response and Context.
Your school chooses your context for you, and you study texts related to that context. My context is horrible, it is Identity and Belonging, which is part of the reason I'm typically disinterested in English for the most part.