Are there differences between writing an essay and a presentation (or conference paper?)
Yeah, I mean, I think typically there [are] two kinds of differences: one is, when you publish in a journal the readership is the readership of that journal. When you give a talk at a conference, the people who are in the room listening to your talk are the people who are interested in that narrow subject, or else they're your friends. So, you can be much more focused on a small topic in a conference presentation. Conference presentations are typically 4000 words instead of 8000 words, say, for a journal article. So, you can say a lot less and things tend to be much more focused. But also, it's much more important when you give a talk to be clear, to have your audience with you, and to follow you, and to...so, in that sense to write engagingly and to speak engagingly.