A project sponsor is the person who is behind the project ie the person who really wants it done. The sponsor might be the marketing director who wants much more information about what visitors to the company’s website do; or the sponsor might be the HR director who wants a sophisticated 360 degrees appraisal system introduced. Often payment for the project will come out of the sponsor’s budget.
The project manager is the person who is in day-to day charge of the project and who organises the project team. The project managers might not be a permanent employee of the company and is often a consultant brought in for the duration of the project.