The difference between Slide Design and Auto Content Wizard is

The AutoContent Wizard creates a new presentation using built-in templates, offering sample content ideas to help we organize the information we include on each slide. This feature is not available in Microsoft Office PowerPoint 2007 and higher versions. Instead, we can create our presentation quickly and easily by using templates.
Slide Design provided different theme, variants, size which we need to apply as per our requirement. It does not provide sample content.