What is the difference between a coupled roof and a non-coupled roof?

From AS 1684.4 Residential Timber Framing Code

2.6.4.1 Coupled roof

Pitched roof construction with a roof slope not less than 10°, with ceiling joists and collar ties fixed to opposing common rafter pairs and a ridgeboard at the apex of the roof (see Figure 7.1). A coupled roof system may include some area where it is not possible to fix ceiling joists or collar ties to all rafters, e.g., hip ends or parts of T- or L-shaped house.

2.6.4.2 Non-coupled roof

A pitched roof that is not a coupled roof and includes cathedral roofs and roofs constructed using ridge and intermediate beams.