Use the Slider content type in full-width areas when you want to feature specific topics or categories of content. When selecting images, use the small variant.
Use the Gray Background Links content type in full-width areas for offering up to 9 options to the user. If only one option, use the Block Button content type.
Use the Call-out Slab content type for featured content you really want the visitor's eyes drawn to... used for important/prominent content.
Use the Feature Box with Blue Button content type when you want to feature up to 6 topics or categories of content. When choosing images, select the large variant.
Use the Blue Boxes on Image Background content type when featuring up to 8 options/links.
Use the List Block content type when offering a lot of links (up to two sections) in full-width areas... can also be used in the main content area with a sidebar, but in that case only use the first set of links.