Motivational Speaker
A motivational speaker is a speaker who makes speeches intended to motivate or inspire an audience. Such speakers may attempt to challenge or transform their audiences. The speech itself is popularly known as a pep talk.
Motivational speakers can deliver speeches at schools, colleges, places of worship, companies, corporations, government agencies, conferences, trade shows, summits, community organizations, and similar environments
Public speaking (also called oratory or oration) has traditionally meant the act of speaking face to face to a live audience but today includes any form of speaking (formally and informally) to an audience, including pre-recorded speech delivered over great distance by means of technology.
Public speaking is used for many different purposes, but usually as some mixture of teaching, persuasion or entertaining. Each of these calls upon slightly different approaches and techniques.
Public speaking was developed as a sphere of knowledge in Greece and Rome, where prominent thinkers codified it as a central part of rhetoric. Today, the art of public speaking has been transformed by newly available technology such as videoconferencing, multimedia presentations, and other nontraditional forms, but the essentials remain the same.
The function of public speaking depends entirely on what effect a speaker intends when addressing a particular audience. The same speaker, with the same strategic intention, might deliver a substantially different speech to two different audiences. The point is to change something, in the hearts, minds or actions of the audience.
Despite its name, public speaking is frequently delivered to a closed, limited audience with a broadly common outlook. Audiences may be ardent fans of the speaker; they may be hostile (attending an event unwillingly); or they may be random strangers (indifferent to a speaker on a soap box in the street). All the same, effective speakers remember that even a small audience is not one single mass with a single point of view but a variety of individuals.
As a broad generalization, public speaking seeks either to reassure a troubled audience or to awaken a complacent audience to something important. Having decided which of these approaches is needed, a speaker will then combine information and storytelling in the way most likely to achieve it.
Source: https://en.wikipedia.org/wiki/Motivational_speaker
https://en.wikipedia.org/wiki/Public_speaking