Many people use the words "speech" and "presentation" interchangeably since both involve speaking in front of a group. It's true that both can be dreaded for that very reason. Others note the difference is that speakers in a presentation use visual aids, while those in a speech typically don't. While that's true enough, there are many other distinct differences between the two.
Don't tell the speaker giving a presentation in front of the company CEO and other bigwigs that it isn't a formal occurrence. His sweaty palms say otherwise. But, nervousness aside, presentations are given many times throughout the year in business, from sales meetings to conferences, while speeches are reserved for high profile, public events and special occasions like retirement parties and company mergers. Because of this, speeches are more formal. Not that the speaker has to wear formal attire; if only it were that simple to pull off a great speech! Also, the audience is more interested in what your presentation will show them, than they are in you and how you present. Whereas in a speech, it’s just you up there, so all eyes and ears are on you.
If you think speeches tug at the listeners' emotions while presentations present the facts with visual backup, you're partially right. Speeches make use of anecdotes that pull you in. As you listen you may be thinking, "That's happened to me too!" Or, if the story is unique or outlandish, it leaves you feeling amazed that such a thing happened to the speaker. Stories people can relate to can help presentations, too, but they're not as critical and they can even be distracting. You're already talking and showing visuals; adding stories can seem like too much of a diversion.
Caring about your work always makes it better. But in a presentation, you can and should dazzle people with your visuals. They're not your backup; they're as critical to your presentation as your explanations. It's a lot like show-and-tell. Without the things to show, you'd have nothing to tell. If you make sure all the charts and graphs you show are easy to understand, your audience will get your messages. A speech, on the other hand, is just you. This is where your passion really comes through, or your lack of it turns your speech into a dud. It's important to decide what your speech's core message is, then build out from that with quotes, anecdotes and humor to convey your message in a memorable way.
You may be wondering about other types of public speaking. What's the difference between a seminar and a presentation; or a speech and a lecture? How about the difference between a speech and a debate?
A seminar is different from a presentation in that it's more interactive. While a presentation is given by one person, a seminar involves the participants in some way. It could include small group discussions or a panel. Since seminars are typically several hours in length, they often have many parts that vary in structure to keep people interested.
A lecture is similar to a speech because both are rather formal and one person is doing the talking. Lectures are more often used to teach something, particularly in a college class. Since lectures are typically given during every class period, they aren't expected to be as dramatic or dynamic as a speech, though it might be more motivating if they were!
A debate differs from both a speech and a presentation because it's between two sides that are equally involved. Each side usually takes an opposing view on the debate question or subject. It's often like a contest where, at the end of it, a vote is taken to decide who won the debate.