There are a few things that construct the portal content:
1) iView (we refer to this primarily)
2) Portal Page
3) Workset
4) Role
for delivery:
5) Business Package
An iView is basically an integrated platform for the web application to present contents.
A Portal Page can contain multiple iView the layout them in different positions. Worksets contain a set of portal pages and iViews that perform particular functional task, i.e. Executive Reporting function for executive group. While yo can assign a group of worksets to a role, then assign the role to an user so that he/she can see the contents of the worksets in the portal.
For delivery or content migartion, we can package all the objects (iViews, pages, worksets, and roles) in a unit call sda (software development archieve) as a Business Package.
(The print screen below will give you some idea on the explanation above.)