The Places API implementation at present, only caters for search results of type PlaceResult meaning only places are ever returned from a search query. In future a QueryResult type can be introduced. The QueryResult enables the user to do a further search, this could be in the form of a “Did You Mean” suggestion e.g. the user makes a typo and searches for “piza”, the QueryResult could have a title “did you mean pizza” and have an appropriate search request for that.
A related use case is to only provide a search center and be given back both Place Results and Query Results. The Query Results can refer to categories and be used to do a more refined search to find more places and more (sub)categories. This process can potentially be recursive. This functionality was known as Explore and facilitates context sensitive searching for nearby places and categories rather than having a static category tree. The Nokia Places REST API service provides explore functionality, see http://api.maps.nokia.com/en/restplaces/api.html#__The_Explore_Resources#ID
There is a work in progress patchset that implements QueryResults at https://codereview.qt-project.org/#change,20727.