Hendon Group, Inc. defines projects, programs and portfolios as follows:
Projects
Projects are temporary work efforts undertaken to create a unique result, product or service.
Programs
Programs are a group of related projects that are managed and coordinated in such a way to deliver additional control and benefits not achievable if the projects were managed independently.
Portfolios
Portfolios are a collection of programs and projects grouped together to support the achievement of one or more strategic organizational objectives.