b4035917_roject__Program__and_Portfolio__Portfolio
[Characteristic] Scope [Project] At a given time, a project has a scope limited to meeting its objectives, including delivering the planned product. The scope is developed and monitored and controlled throughout the lifecycle of the program by using progressive elaboration. [Program] A program has a wider scope dedicated to meeting the benefits in context of the strategic goals of the organization. [Portfolio] 
A portfolio has a business scope that changes with the change in the strategic plan and goals of the organization.
Become a Certified Project Manager: Chapter 13: Relationship between Project, Program, and Portfolio
Portfolio