Answer: Swiss Binding!
This is a form of Swiss binding in which the text block is mounted to the inside back cover of a hard case. In this instance another text block is mounted to the inside front cover. The actual spine is left free and visible.
“Swiss binding” does not refer to how your pages are bound together but rather to the way the text block (consisting of already bound printed pages) is mounted inside a case.
While you see this method most often used in combination with Smyth binding, you can also choose to Perfect Bind, Saddle Stitch or Side Sew the inside pages. What makes it Swiss bound is when the text block is fully glued to the inside back cover of the case that holds your book.
