In public relations and communication sciences, audiences are groups of individual people, and the public (a, k, a. The general public) is all of these groups. Audiences are the group of people who influence the business activities of a company or people who have a real or potential interest in the company. This audience is responsible for building the image of your company among customers or the industry.
The public are the people who form a community, a state or a nation, as in When a government increases taxes, the public has a right to know. In this context, only one person is a member of the public. When you look in the dictionary, you'll find that “public” means an organized or general group of people.