b4035917_roject__Program__and_Portfolio__Portfolio
[Characteristic] Management [Project] Project manager manages or coordinates the project team to lead the project to its success. [Program] Program manager manages the program staff and the project managers and provide overall leadership, including vision. [Portfolio] 
Portfolio manager may coordinate or manage the portfolio management staff.
Become a Certified Project Manager: Chapter 13: Relationship between Project, Program, and Portfolio
Portfolio