The two technologies aren't synonymous, although they are very similar. An enterprise portal is just that: a portal. It is a browser-based gateway to integrated information and applications to promote information sharing, consistency, and accessibility to members of the organization. An executive dashboard, although it uses the same underlying technology, is a much smaller-scale subset of portal technology that provides specific, performance-based information to upper-level management.
A dashboard is a one-screen "cockpit" of all critical measurements for driving business decisions, offering actionable information at management's fingertips, business performance measurements at a glance, and up-to-date information on status and forecasts against benchmarks. Executive dashboards are an absolute must for any organization that wants to keep a finger on the pulse of its business activities.
There are two major differences between enterprise portals and executive dashboards: scope and purpose. A portal's scope is organization wide; it serves as a single-point that connects all the partners in an organization's value chain. Customers, vendors, employees, executive management, anyone or any organization that's a stakeholder can be a portal user. For example, employees can access SAP functionality, customer information, sales databases, stored documents, from anywhere in the organization via the Internet. Customers can access such things as inventory, call up sales histories, download marketing materials, and place or check the status of orders. In essence, a portal is an enterprise wide gateway to manage traffic up and down stream.