In case of portals, the story is reasonably clear.  I think most would agree that the goal of portals is to provide users with integrated access to relevant business information.  The key words here are: access, integrated and relevant.  So, it’s a “one stop shopping” for information gathered from structured (databases, etc.) and unstructured (e-mails, lists, documents, etc.) data from disparate sources across the enterprise.  To support this goal, good portals come with indexing and full-text search across all these data sources, comprehensive collaboration support, and are, in a sense, a launching pad for other applications, web sites, etc.

But when talking about dashboards and scorecards, the differences become a bit less clear.  Recently, I came across a white paper titled “The essential guide to analytic dashboards”.  The author (Aaron Solomon) has made it as clear as it gets, in my opinion.  Here is a chart from his paper:

Given these definitions, a dashboard is best fit for tracking key performance indicators at a tactical level, for measuring performance and analyzing data via a relatively structured, analytic view.  A dashboard often is incorporated into a portal.

A scorecard is a great tool for aligning user activities to key strategic objectives. 

I encourage you to read Aaron’s white paper by visiting http://www.windowsitpro.com/cluster/docs/products/1/3/Proclarity_EG.pdf.