The structure is a slightly more abstract manifestation of the skeleton. It shows a basic understanding of how users navigate through the app. It refers to the different categories and sections of the app, rather than the actual placement of the elements.
A large part of interaction design is the behavior of the users towards your app. Information architecture and sitemaps define the navigational settings — how people react to the various features on the app. Low fidelity wireframes are a useful way to have your users navigate through the app and provide you with useful insight on what parts of the structure may not work for them.
Printable wireframe templates.