The title is the same as the title of a Confluence page. As you well know, a title has to be unique within a space (unless you have deployed some fancy plugins that help you to get rid of this constraint).

The name on the other side should be unique within the document type. That is there must exist no two documents within a search space with the same name and doctype. Whereas the unique constraint of the title within its space is tightly enforced, there is no checking for the uniqueness of the name. This is due to the fact that the search space is defined at search time, while the name is specified at writing time.

The name allows you to have documents of different types with the same name. It might happen that you want to have your resources and your topics in the same space. If you have a resource, a book, called "Continuous Delivery" and also you want to collect resources on the topic "Continuous Delivery", your are free to do so. All you have to decide is how to name the title of the document. In case of resources we usually take the last name of the first author and add the publication date of the resource (e.g. Humble2010).

If you have two documents with the same name, you simply won't have a single match on a name query. If a particular macro expects exactly one match, it will arbitrarily choose one.