Display all items, or as many as possible, as a grid. This would work for collections that have significant visual elements, like Collection 15.
Make it more clear that the list of items is just a partial list, and users must follow a link to the items/browse view to browse all the items in the collection.
Combine, somehow, the collections/show view with the items/browse view. maybe, if the list of items is narrowed by a particular collection, display that collection's information somewhere.
Some ideas: