In "Read Mode" you will only see the published content. 
In "Edit Mode" you could see also content in the status "Draft".

Tree view is the default view for your Domains and Data Templates.

Click the domain to open the detail panel.

Click "Properties" to see properties associated with current domain or data template.

List view is a flatten list for all domains or data templates in the dictionary.

Click "Graph2d" to see all element relations in a graph.

Here is a representation for relations of domains.