Portal vs. portal

How is it that CMS and Portals systems are blurry? Its clear that a CMS system with LOTS of work can also be made to look like a portal, but underneath its not easy to maintain and reuse. Portal servers have builtin maintainability with nice administrative tools to deploy/undeploy mini applications within a portal layout.

If you try and use a CMS for this purpose, you'll be wasting a lot of effort in trying to accomplish what a portal server already provides. On the other hand, portals also also not CMS systems, but can have a portlet application that handles CMS functionalities.

Basically portal servers manage mini plugable applications while CMS manages content and the business flow for that content. CMS systems should be integrated into portals server via portlets.