The Slide Design concepts presented focus on:

 The visual aspects of the presentation.

  The content's conciseness and clarity.

This "Slide Design" book is a "how-to" design a slide-show presentation, that helps:

 The audience follow the presentation;

 The speaker present rather than read notes;

 The speaker build goodwill for him/herself.

What language is he speaking?

in class presentation can be found here.

The Slide Design concepts presented focus on:

 The visual aspects of the presentation.  In particular:

 How to use: images, numbers, bullet points…

 The content presented. More precisely:

 How to focus on conciseness, by

 Paying attention to the wording of sentences…

 The clarity of the slides:

 Using one idea per slide

 Using a slide to demonstrate a point

 Introducing the idea in the title