There’s a difference.
You can prepare yourself. You might memorize your speech, or choose your outfit. You could review your notes just before you go on.
But preparing for your audience is different. It requires thinking about the entire experience from their viewpoint. What do they want to hear? How do they hope to feel when it’s over? Do they need to learn something in particular? How can you create your talk to lead to the outcome they’re interested in ( or that they’ll be surprised and delighted by?)
Sometimes (often, actually) we have to sacrifice some of what makes us feel comfortable in order to maximize the audience’s experience. Instead of reading our notes, which can feel comfortable for us, we can prepare for our audience by familiarizing ourselves with our content so we don’t have to read. Instead of concentrating on the message we want to deliver, we can spend time focusing on what our audience is there for.
This is a balance. Of course we need to feel personally prepared to take the stage. But part of that preparation should include a thorough survey of what it will take to make this investment of time worthwhile for the audience.