The two types of recommendations can be used in different locations in your shop.

Product detail page (cross/upsell only)

A product detail page is one product's display. On this page, you can find other related products that match with the selected product. They will normally be in the following locations with a default Magento setup:

Category page (featured products only)

The product overview page lets you display a selection of products. Normally, they will be at the bottom of the page. So below the product display:

Content page (featured products only)

You can place a featured products widgets on any position on a content page. Make sure it's a Tweakwise - featured products widget.