Application Portfolio
It involves management of complete group or subset of software applications in a portfolio.
These applications are considered as investments as they involve development (or acquisition) costs and maintenance costs.
Product Portfolio
The product portfolio management involves grouping of major products that are developed and sold by businesses into (logical) portfolios. These products are organized according to major line-of-business or business segment.
Project Portfolio
It is also referred as an initiative portfolio management where initiative portfolio involves a defined beginning and end; precise and limited collection of desired results or work products; and management team for executing the initiative and utilizing the resources.