The reason is that the author uses rather weak definitions of the core terms. The article proposes three components: 1. Aesthetic Design, 2. Interface Design and 3. Information Design. These terms are not very specific in their application to web design – and yet the article uses rather narrow definitions.
But a better terminology for the core question the article is raising would be
- Visual Appearance
- Interaction Design
- Information Architecture
With these terms a reader would find much more useful information.
Content, structure and form
Any design problem can be separated into questions of content, structure and form. This is most simple approach is to reflect them (even web design). A given design task touches three domains:
- Making sense with given CONTENT
- Creating appropriate STRUCTURE
- Finding the optimal FORM
And this is how these three domains relate to the terms I proposed above:
- Visual Appearance asks »How does FORM interact with CONTENT?«
- Interaction Design asks »How does STRUCTURE interact with FORM?«
- Information Architecture asks »How does CONTENT interact with STRUCTURE?«
_PS: While I have concerns about that particular article I think the PSDTUT website offers a lot of very good tutorials. The site even offers a $9/month plus membership with additional material for people with professional ambitions. I think that is a very fair deal!