Demurrage vs detention in Australia

Same idea, opposite sides of the gate

Demurrage is the charge for leaving a full container on the wharf beyond free time, before you collect it. Detention is the charge for holding the carrier's container off-terminal, in your yard or at the packer, beyond free time, until you dehire the empty.

A simple test: if the box is still inside the terminal, a delay is demurrage. Once it leaves the gate, a delay is detention.

Why the distinction changes who you argue with

Demurrage disputes turn on terminal availability and slot booking. Detention disputes turn on empty-park capacity and dehire acceptance. A full park that will not take your box is a detention problem, not a parking one, and the evidence you need is different for each.