What is an automatic and manual mode for a checkout agreement?

Magento 2 checkout agreement admin screen contains a new dropdown option Applied (absent in Magento 1.x) with 2 options: Automatically and Manually.

Manual mode

Manual mode is the mode from Magento 1.x.
A customer must click a checkbox to agree with the shop rules.

Automatic mode

Manual mode is a new Magento 2 mode (absent in Magento 1.x.)
A customer can (but is not obliged) click the agreement link to see the shop rules.