In France, the Chairman of the company is the one who will be appointed in the United States as CEO (Chief Executive Officer) and in UK as Director ... They are the legal representatives of the company and have a leading role. The C-levels are the other officers (Chief Marketing Officer, Chief Technical Officer, Chief Legal Officer ...), appointed 'directors' in France; they may have the same role and the same powers as the CEO according to the provisions in the bylaws.
The shareholders all have shares in the company, they may be officers or not. The founders are distinguished from the other partners because they are the ones who created the company (their names appear in the bylaws of incorporation).
The specific legal powers of directors vary according to the form of the company, but to simplify discussions with foreign investors (who is who and who does what?), most executives refer to themselves as CEOs for the Chairman and C-level for the other leaders and co-founder when they were at the origin of the project.
This use is authorized provided that the official documents state that the CEO acts as Chairman. In fact, the official documents will mention the title of Chairman and business cards or your Linkedin profile, CEO (Chairman).
The most common approach to start healthily and cautiously with madeinlaw.com is to appoint the CEO and C-level leaders. They therefore all represent the company under the same powers and are subject to the same legal responsibilities.