Public speaking can be hard enough, but what about speaking in public where you have to improvise and be spontaneous and where your role is the ring master and major motivator? That is the role of the emcee.
I have been the emcee before at big and small events, and I can tell you from personal experience - it is a tough gig and probably one of the most challenging speaking opportunities that I've ever had. To be an emcee you have to be both prepared and spontaneous. You have to be prepared with the flow and timing of the event, you have to know well the people you are introducing and every element within the entire event. But also, you have to spontaneous. As an emcee, I have had to quickly make adjustments in the program, be able to be witty and funny at unplanned moments and make the best of unforeseen issues (i.e. audio and visual problems).
Here is a excerpt from good post about from Eric Feng on How to Emcee like a Pro.
Here is a quote from the interview:
How is emceeing different from what you mainly do in Public Speaking? (Presenting prepared speeches)
Eric: As an emcee, you are essentially the cheerleader. No matter what, you have to have you're 1000 Watts smile and you're energy has got to be at least 3X more than your audience. It all starts with YOU, really. YOU decide, if they're going to have a great time or not. Of course, humor is much appreciated :)
Gary: Giving speeches are mostly one-sided. Sure there's the occasional interaction and audience response. But emceeing is different in a way that its about actively, VERY ACTIVELY managing and raising the energy of the audience.
Sabrina: Giving speeches is more orchestrated and emceeing can be rather spontaneous. You have to be prepared to be spontaneous anyway. I think naturally when you deliver a prepared speech, you're more likely to worry about your performance. But as an emcee, you're more likely to be worried about the event running smoothly.