Project Sponsor in Project Management
This appears to be one of the most popular search queries on Google, so I will explain. A project manager is tasked to deliver a project with a specified performance level and within a set budget and timescale. He or she then organizes a team to do that.
The Project Sponsor is the person who has assumed the role within the organization of identifying and defining the project, such that it delivers a required change consistent with corporate strategy that adds value to the organization.
For an amusing, and hopefully informative article on the difference between the Project Manager and Project Sponsor see my post
And for much, much more take a look at my book on project sponsorship