After having created a connection, you can see a connection node being created in your configurable tree. In the screenshot below, the (expanded) os_default node would be a default connection, the Oracle8View connection would be a user-created connection:
Each connection node has questions and question groups.
A question is the simplest unit inside a connection. This allows you to access/monitor one single aspect of a connection. This is typically a simple query being fired on the target software layer using the settings provided by you when you created the connection.
A question group is a preconfigured set of questions that can be executed by the user in one shot. The result can be reviewed in a grouped manner.