Web as software interface
Visual Design: graphic treatment of interface elements (the "look" in "look-and-feel")
Interface Design: as in traditional HCI: design of interface elements to facilitate user interaction with functionality
Information Design: in the Tuftean sense: designing the presentation of information to facilitate understanding
Interaction Design: development of application flows to facilitate user tasks, defining how the user interacts with site functionality
Functional Specifications: "feature set": detailed descriptions of functionality the site must include in order to meet user needs
User Needs: externally derived goals for the site; identified through user research, ethno/techno/psychographics, etc. Site Objectives: business, creative, or other internally derived goals for the site

Web as hypertext system
Visual Design: visual treatment of text, graphic page elements and navigational components
Navigation Design: design of interface elements to facilitate the user's movement through the information architecture
Information Design: in the Tuftean sense: designing the presentation of information to facilitate understanding
Information Architecture: structural design of the information space to facilitate intuitive access to content
Content Requirements: definition of content elements required in the site in order to meet user needs
User Needs: externally derived goals for the site; identified through user research, ethno/techno/psychographics, etc.
Site Objectives: business, creative, or other internally derived goals for the site