Use 1st-person and don't go overboard with colloquialism. The idea is to engage and persuade the audience to see your view or at least what you are trying to present. But no, it doesn't differ too greatly from an essay. Just make sure you can present well and then an essay-style answer will suffice. Although, I suppose that the intro and conclusion may be a bit different... Mostly the same concept, a thesis and a generalised view of your texts and the themes they present, but just try to make it more engaging to stick in the mind of the audience, or in this case, the marker.